add M1 build with compilers from macports #471

Job	Run time
build (ubuntu-latest, gfortran, cmake)	15m 27s
build (ubuntu-latest, gfortran, make)	8m 5s
build (ubuntu-latest, flang, cmake)	15m 49s
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	5m 2s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	4m 30s
build (ubuntu-latest, flang, make)	6m 37s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	5m 45s
build (macos-latest, gfortran, cmake)	32m 57s
build (macos-latest, gfortran, make)	12m 54s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	4m 29s
msys2 (MINGW64, int32, Release)	46m 59s
msys2 (MINGW64, int64, Release)	57m 19s
msys2 (MINGW32, int32, Release)	1h 14m 1s
msys2 (CLANG64, int32, Release)	58m 51s
msys2 (CLANG64, int64, Release)	52m 37s
msys2 (CLANG32, int32, Release)	17m 42s
msys2 (MINGW64, int32, None, mingw-w64-x86_64, fc)	30m 46s
	7h 29m 50s

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