powerpc: Re-enable VDSO support
powerpc: Re-enable VDSO support

Powerpc requires VDSO support in order to produce a stack trace.
Without this, it isn't possible to complete a build.
Tested on powerpc, powerpc64 and powerpc64le.

acmorrow/gperftools,gperftools/gperftools,romange/gperftools,romange/gperftools,romange/gperftools,acmorrow/gperftools,gperftools/gperftools,romange/gperftools,gperftools/gperftools,alk/gperftools,gperftools/gperftools,alk/gperftools,acmorrow/gperftools,alk/gperftools,alk/gperftools,acmorrow/gperftools