Clean up paths using filepath package

When reconciling samples, cleanup file paths to allow functions to be
combined if their source filenames match after cleanup (eg "src.cpp" and
"./src.cpp").

Also clean up existing uses of filepath to avoid passing empty strings
to it: filepath.Base("") returns "."

internal/driver/driver.go

 		OutputUnit: vars["unit"].value,
 	}
 
-	if len(p.Mapping) > 0 {
+	if len(p.Mapping) > 0 && p.Mapping[0].File != "" {
 		ropt.Title = filepath.Base(p.Mapping[0].File)
 	}
 

internal/driver/testdata/pprof.contention.cum.files.dot

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Build ID: buildid-contention" [shape=box fontsize=16 label="Build ID: buildid-contention\lComment #1\lComment #2\lType: delay\lShowing nodes accounting for 149.50ms, 100% of 149.50ms total\l"] }
 N1 [label="file3000.src\n32.77ms (21.92%)\nof 149.50ms (100%)" fontsize=20 shape=box tooltip="testdata/file3000.src (149.50ms)" color="#b20000" fillcolor="#edd5d5"]

internal/driver/testdata/pprof.contention.flat.addresses.dot.focus.ignore

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Build ID: buildid-contention" [shape=box fontsize=16 label="Build ID: buildid-contention\lComment #1\lComment #2\lType: delay\lShowing nodes accounting for 40.96ms, 27.40% of 149.50ms total\l"] }
 N1 [label="0000000000001000\nline1000\nfile1000.src:1\n40.96ms (27.40%)" fontsize=24 shape=box tooltip="0000000000001000 line1000 testdata/file1000.src:1 (40.96ms)" color="#b23900" fillcolor="#edddd5"]

internal/driver/testdata/pprof.heap.flat.inuse_space.dot.focus

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Build ID: buildid" [shape=box fontsize=16 label="Build ID: buildid\lType: inuse_space\lShowing nodes accounting for 62.50MB, 63.37% of 98.63MB total\l"] }
 N1 [label="line2001\nfile2000.src\n62.50MB (63.37%)" fontsize=24 shape=box tooltip="line2001 testdata/file2000.src (62.50MB)" color="#b21600" fillcolor="#edd8d5"]

internal/driver/testdata/pprof.heap.flat.inuse_space.dot.focus.ignore

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Build ID: buildid" [shape=box fontsize=16 label="Build ID: buildid\lType: inuse_space\lShowing nodes accounting for 36.13MB, 36.63% of 98.63MB total\lDropped 2 nodes (cum <= 4.93MB)\l"] }
 N1 [label="line3002\nfile3000.src\n31.25MB (31.68%)\nof 32.23MB (32.67%)" fontsize=24 shape=box tooltip="line3002 testdata/file3000.src (32.23MB)" color="#b23200" fillcolor="#eddcd5"]

internal/driver/testdata/pprof.heap.flat.lines.dot.focus

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Build ID: buildid" [shape=box fontsize=16 label="Build ID: buildid\lType: inuse_space\lShowing nodes accounting for 67.38MB, 68.32% of 98.63MB total\l"] }
 N1 [label="line3000\nfile3000.src:4\n0 of 67.38MB (68.32%)" fontsize=8 shape=box tooltip="line3000 testdata/file3000.src:4 (67.38MB)" color="#b21300" fillcolor="#edd7d5"]

internal/driver/testdata/pprof.heap_alloc.flat.alloc_space.dot.focus

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Build ID: buildid" [shape=box fontsize=16 label="Build ID: buildid\lType: alloc_space\lShowing nodes accounting for 93.75MB, 95.05% of 98.63MB total\lDropped 1 node (cum <= 4.93MB)\l"] }
 N1 [label="line3002\nfile3000.src\n31.25MB (31.68%)\nof 94.73MB (96.04%)" fontsize=20 shape=box tooltip="line3002 testdata/file3000.src (94.73MB)" color="#b20200" fillcolor="#edd5d5"]

internal/driver/testdata/pprof.heap_alloc.flat.alloc_space.dot.hide

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Build ID: buildid" [shape=box fontsize=16 label="Build ID: buildid\lType: alloc_space\lShowing nodes accounting for 93.75MB, 95.05% of 98.63MB total\lDropped 1 node (cum <= 4.93MB)\l"] }
 N1 [label="line3000\nfile3000.src\n62.50MB (63.37%)\nof 98.63MB (100%)" fontsize=24 shape=box tooltip="line3000 testdata/file3000.src (98.63MB)" color="#b20000" fillcolor="#edd5d5"]

internal/graph/graph.go

 			if line.Function != nil {
 				ni.Name = line.Function.Name
 				ni.OrigName = line.Function.SystemName
-				ni.File = line.Function.Filename
-				ni.StartLine = int(line.Function.StartLine)
+				if fname := line.Function.Filename; fname != "" {
+					ni.File = filepath.Clean(fname)
+				}
+				if keepBinary {
+					ni.StartLine = int(line.Function.StartLine)
+				}
 			}
 			if keepBinary || line.Function == nil {
 				ni.Objfile = objfile

internal/report/report_test.go

 import (
 	"bytes"
 	"io/ioutil"
-	"path/filepath"
 	"regexp"
 	"testing"
 
 				&Options{
 					OutputFormat: List,
 					Symbol:       regexp.MustCompile(`.`),
-					Title:        filepath.Base(testProfile.Mapping[0].File),
 
 					SampleValue: sampleValue1,
 					SampleUnit:  testProfile.SampleType[1].Unit,
 					OutputFormat: Dot,
 					CallTree:     true,
 					Symbol:       regexp.MustCompile(`.`),
-					Title:        filepath.Base(testProfile.Mapping[0].File),
 
 					SampleValue: sampleValue1,
 					SampleUnit:  testProfile.SampleType[1].Unit,

internal/report/testdata/source.dot

-digraph "." {
+digraph "unnamed" {
 node [style=filled fillcolor="#f8f8f8"]
 subgraph cluster_L { "Duration: 10s, Total samples = 11111 " [shape=box fontsize=16 label="Duration: 10s, Total samples = 11111 \lShowing nodes accounting for 11111, 100% of 11111 total\l"] }
 N1 [label="tee\nsource2:8\n10000 (90.00%)" fontsize=24 shape=box tooltip="tee testdata/source2:8 (10000)" color="#b20500" fillcolor="#edd6d5"]

internal/symbolizer/symbolizer.go

 
 		// Skip well-known system mappings
 		name := filepath.Base(m.File)
-		if name == "" || name == "[vdso]" || strings.HasPrefix(name, "linux-vdso") {
+		if m.File == "" || name == "[vdso]" || strings.HasPrefix(name, "linux-vdso") {
 			continue
 		}
 

internal/symbolizer/symbolizer_test.go

 		ID:    1,
 		Start: 0x1000,
 		Limit: 0x5000,
+		File:  "mapping",
 	},
 }