cleanup to remove ifdefs around functions affected by
a clang bug.

gn gen out/Release "--args=is_debug=false target_os=\"android\" target_cpu=\"mips64el\" mips_arch_variant=\"r6\" mips_use_msa=true is_component_build=true is_clang=true"
ninja -v -C out/Release libyuv_unittest

Bug: libyuv:634
Test: build for mips with clang
Change-Id: I278b368dbb2fe89082240e280267d0a27a214c78
Reviewed-on: https://chromium-review.googlesource.com/757980Reviewed-by: Frank Barchard <fbarchard@google.com>
Commit-Queue: Frank Barchard <fbarchard@google.com>