crt: Use aarch64 assembly variants for ARM64EC math functions. #26

Job	Run time
gcc (ucrt, i686)	27m 50s
llvm-mingw (msvcrt)	23m 44s
llvm-mingw (ucrtbase)	22m 45s
gcc (ucrt, x86_64)	29m 10s
gcc (msvcrt, x86_64)	29m 19s
gcc (msvcrt, i686)	32m 59s
llvm-mingw (ucrt)	24m 3s
test-libcxx (x86_64)	1h 10m 18s
test-libcxx (x86_64, i686-w64-mingw32-)	1h 12m 14s
test-ffmpeg (x86_64)	17m 9s
test-ffmpeg (i686)	16m 47s
test-llvm-mingw (x86_64, ucrtbase)	3m 44s
test-llvm-mingw (x86_64, msvcrt)	3m 40s
test-llvm-mingw (x86_64, ucrt)	3m 43s
test-llvm-mingw (i686, ucrtbase)	3m 35s
linux-test-cross-build-ffmpeg (x86_64)	5m 52s
linux-test-cross-build-ffmpeg (i686)	4m 55s
test-llvm-mingw (i686, msvcrt)	3m 49s
linux-test-cross-build-ffmpeg (armv7)	4m 41s
linux-test-cross-build-ffmpeg (aarch64)	4m 47s
test-llvm-mingw (i686, ucrt)	3m 50s
gcc-cross (msvcrt, x86_64)	19m 40s
gcc-cross (ucrt, i686)	19m 4s
gcc-cross (ucrt, x86_64)	18m 3s
gcc-cross (msvcrt, i686)	16m 49s
test-gcc (ucrt, i686)	44s
test-gcc (msvcrt, x86_64)	47s
test-gcc (ucrt, x86_64)	42s
test-gcc (msvcrt, i686)	36s
	8h 5m 19s

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