This will enable symbolization support for Go on Mac OS
It re-enables symbolization using debug/pprof/symbol on
Go profiles in the legacy format, and implements basic
mach-O support on the binutils package.

pprof fetches profiles concurrently, which allows to profile multiple running
servers concurrently. However, this may translate into a large use of memory
if many profiles are merged, as pprof attempts to decode all profiles in parallel.

Limit the concurrency by chunking the concurrent fetches in groups of up to
64 profiles.

Also update the build instructions to use go get