emulators/mupen64plus-video-glide64mk2: unbreak with clang 3.9

./../src/Glide64/3dmath.cpp:274:5: error: use of undeclared identifier '__builtin_ia32_storeups'

__builtin_ia32_storeups(r[i], destrow);
^

PR: 212343
Regressed by: https://github.com/llvm-mirror/clang/commit/53a73530fec1