multimedia/obs-studio: fix build on powerpc64le

/wrkdirs/usr/ports/multimedia/obs-studio/work/obs-studio-30.2.3/libobs/graphics/../util/simde/x86/sse2.h:1793:58: error: Current handling of vector bool and vector pixel types in this context are deprecated. The default behaviour will soon change to that implied by the '-altivec-compat=xl' option [-Werror,-Wdeprecated-altivec-src-compat]
1793 | r_.i64 = HEDLEY_STATIC_CAST(typeof(r_.i64), (a_.f64 != b_.f64));