Allow to trim paths in pprof file before importing it

[narqo]

Ref google/pprof#366

When we import a bunch of pprof files, we want to specify locations' common prefix, that must be trimmed before files were processed by the collector. This will reduce the amount of data stored in (the current implementation of postgres) storage.

This will require parsing pprof file before sending it to the collector, so it's likely that importer will have to be rewritten from a bash script to Go.

[narqo]

Go 1.13 adds -trimpath build flag to

[..] remove all file system paths from the compiled executable, to improve build reproducibility.

See https://tip.golang.org/doc/go1.13#go-command