gprofng: do not skip weak symbols

PR gprofng/33151

gprofng ignores functions that are compiled as weak symbols. This
heavily affects C++ class methods that are always compiled by g++
and clang++ as weak symbols. In this case 'gprofng display text'
just displays <static>@ADDRESS(<FILENAME>) instead of proper method
name.

The bug has been introduced in the commit 470a0288a818.