x86 microcode loading and misc fixes #1191

Job	Run time
build-minimal-sysroots (x86_64)	1m 17s
build-minimal-sysroots (riscv64)	1m 22s
build-minimal-sysroots (arm64)	1m 0s
build-toolchains (ubuntu-latest, x86_64, gnu)	40s
build-toolchains (ubuntu-latest, riscv64, gnu)	51s
build-toolchains (ubuntu-latest, arm64, gnu)	37s
build-toolchains (ubuntu-20.04, x86_64, gnu)	30s
build-toolchains (ubuntu-20.04, riscv64, gnu)	41s
build-toolchains (ubuntu-20.04, arm64, gnu)	40s
build-toolchains (ubuntu-latest, llvm, all)	55s
build	3m 15s
build-llvm	2m 51s
build-llvm-arm64	0s
build-arm64	0s
build-llvm-riscv64	2m 53s
build-riscv	3m 7s
run-riscv	0s
run-riscv64-llvm	0s
run-x86_64	0s
run-x86_64-llvm	0s
	20m 39s

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