lang with '-ftrapv' generates 'call __mulodi4', which is only implemented
in compiler-rt library. However compiler-rt library only has i386/x86_64
backends (see '/usr/lib/clang/3.7.0/lib/linux/libclang_rt.*'). Gcc, on the
other hand, generate 'call __mulvdi3', which is implemented in libgcc

Signed-off-by: Khem Raj <raj.khem@gmail.com>