Remove range extension support from LoongArch #4083

Job	Run time
build-gcc	18m 43s
build-macos (-DCMAKE_DISABLE_PRECOMPILE_HEADERS=On)	6m 30s
build-distros (alpine)	14m 58s
build-macos (-DMOLD_USE_ASAN=On)	13m 2s
build-clang (-DCMAKE_DISABLE_PRECOMPILE_HEADERS=On)	11m 35s
build-distros (archlinux)	16m 59s
build-msys	10m 34s
build-clang (-DMOLD_USE_TSAN=On)	17m 34s
build-distros (fedora)	12m 3s
build-distros (gentoo/stage3)	17m 49s
build-windows	28m 43s
build-distros (opensuse/tumbleweed)	11m 27s
	2h 59m 57s

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