CMake: Enable -Werror for the -fno-function-sections check
CMake: Enable -Werror for the -fno-function-sections check

If the -fno-function-sections flag isn't recognized, the compiler
emits a warning. This isn't enough to cause the check to fail, so we
enable -Werror as well.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@200753 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt