LoongArch64: Handle NAN and INF #4135

Job	Run time
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	3m 42s
build (ubuntu-latest, gfortran, cmake)	42m 37s
msys2 (UCRT64, int32, Release)	14m 37s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	2m 30s
build (ubuntu-latest, gfortran, make)	5m 3s
msys2 (UCRT64, int64, Release)	13m 19s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	3m 19s
build (ubuntu-latest, flang, cmake)	10m 14s
msys2 (MINGW32, int32, Release)	17m 16s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	2m 37s
build (ubuntu-latest, flang, make)	5m 11s
msys2 (CLANG64, int32, Release)	20m 35s
build (macos-latest, gfortran, cmake)	1h 4m 16s
msys2 (CLANG64, int64, Release)	17m 27s
build (macos-latest, gfortran, make)	8m 49s
msys2 (CLANG32, int32, Release)	9m 6s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	15m 11s
	4h 15m 49s

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