Travis: Allow job LINUX64_MUSL USE_OPENMP=1 to fail
Travis: Allow job LINUX64_MUSL USE_OPENMP=1 to fail

See: https://github.com/xianyi/OpenBLAS/pull/1255#issuecomment-318692183

kortschak/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,kortschak/OpenBLAS,xianyi/OpenBLAS