Add optimized BGEMM for NEOVERSEN2 target #5947

Job	Run time
build (ubuntu-latest, gfortran, cmake)	45m 42s
build (ubuntu-latest, flang, cmake)	44m 28s
build (ubuntu-latest, flang, make)	9m 30s
neoverse_build	7m 34s
build (macos-latest, gfortran, cmake)	22m 43s
build (ubuntu-latest, gfortran, make)	21m 31s
build (macos-latest, gfortran, make)	6m 34s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	3m 37s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	3m 28s
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	4m 32s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	4m 21s
msys2 (UCRT64, int32, Release)	44m 25s
msys2 (MINGW32, int32, Release)	38m 23s
msys2 (UCRT64, int64, Release)	45m 6s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	42m 9s
msys2 (CLANG64, int32, Release)	33m 39s
msys2 (CLANG64, int64, Release)	30m 35s
	6h 48m 17s

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