gcc: patch out __gnu_linux__ for ppc*-musl
gcc: patch out __gnu_linux__ for ppc*-musl

This macro should not be defined on non-glibc systems. It's not
defined on non-glibc systems on other architectures and has been
removed upstream, too.

[ci skip]

necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages