OpenMP locks instead of busy-waiting with NUM_PARALLEL #4318

Job	Run time
build (ubuntu-latest, gfortran, cmake)	11m 23s
build (ubuntu-latest, gfortran, make)	14m 43s
build (ubuntu-latest, flang, cmake)	10m 54s
build (ubuntu-latest, flang, make)	5m 9s
build (macos-latest, gfortran, cmake)	1h 5m 40s
build (macos-latest, gfortran, make)	21m 6s
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	3m 28s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	7m 34s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	3m 27s
msys2 (UCRT64, int32, Release)	14m 30s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	2m 50s
msys2 (UCRT64, int64, Release)	14m 18s
msys2 (MINGW32, int32, Release)	17m 24s
msys2 (CLANG64, int32, Release)	15m 53s
msys2 (CLANG64, int64, Release)	16m 8s
msys2 (CLANG32, int32, Release)	9m 15s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	13m 42s
	4h 7m 24s

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