x86 microcode loading and misc fixes #1192

Job	Run time
build-minimal-sysroots (x86_64)	50s
build-minimal-sysroots (riscv64)	1m 21s
build-minimal-sysroots (arm64)	56s
build-toolchains (ubuntu-latest, x86_64, gnu)	28s
build-toolchains (ubuntu-latest, riscv64, gnu)	41s
build-toolchains (ubuntu-latest, arm64, gnu)	36s
build-toolchains (ubuntu-20.04, x86_64, gnu)	32s
build-toolchains (ubuntu-20.04, riscv64, gnu)	53s
build-toolchains (ubuntu-20.04, arm64, gnu)	27s
build-toolchains (ubuntu-latest, llvm, all)	53s
build	2m 59s
build-llvm-riscv64	2m 32s
build-riscv	2m 56s
build-llvm	2m 54s
build-arm64	0s
run-riscv	0s
build-llvm-arm64	0s
run-riscv64-llvm	0s
run-x86_64	0s
run-x86_64-llvm	0s
	18m 58s

Provide feedback