Even after local symbolization completes successfully we should
call remote symbolization in case there are some mapping that couldn't
be symbolized otherwise.

Add some tests to ensure both local and symbolz symbolization are called.

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 "."

Also update the build instructions to use go get