Bug#748681: musl libc weak symbol usage incompatible with GCC 4.9

The bug was fixed by upstream gcc and is now found in the GCC-4.9 source tree. Upstream bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61144 Upstream patch: https://gcc.gnu.org/viewcvs/gcc/branches/gcc-4_9-branch/gcc/varpool.c?r1=215896&r2=215895&pathrev=215896

Bug#748733: [4.9/4.10 Regression] Invalid optimizations for extern vars with local weak definitions

Package: gcc Version: 4.9 Severity: important Tags: upstream,confirmed,sid,experimental GCC 4.9 introduced a bug in optimization (present at all -O levels except -O0) in the presence of extern objects with weak definitions local to the translation unit. The following minimal testcase shows the pr