CI: Add m68k/microblaze/powerpc/s390/sh targets. #9

Job	Run time
Source	0s
Build (arm64, aarch64-unknown-linux-musl)	12s
Build (arm32, arm-unknown-linux-musleabi)	9s
Build (arm32hf, arm-unknown-linux-musleabihf)	11s
Build (loong64, loongarch64-unknown-linux-musl)	10s
Build (m68k, m68k-unknown-linux-musl)	8s
Build (microblazeel, microblazeel-xilinx-linux-musl)	10s
Build (microblaze, microblaze-xilinx-linux-musl)	10s
Build (mips64el, mips64el-unknown-linux-musl)	9s
Build (mips64, mips64-unknown-linux-musl)	10s
Build (mips32el, mipsel-unknown-linux-musl)	9s
Build (mips32elsf, mipsel-unknown-linux-muslsf)	10s
Build (mips32, mips-unknown-linux-musl)	9s
Build (mips32sf, mips-unknown-linux-muslsf)	9s
Build (powerpc64, powerpc64-unknown-linux-musl)	16s
Build (powerpc, powerpc-unknown-linux-musl)	16s
Build (riscv32, riscv32-unknown-linux-musl)	11s
Build (riscv64, riscv64-unknown-linux-musl)	11s
Build (s390x, s390x-ibm-linux-musl)	11s
Build (sh, sh-multilib-linux-musl)	22s
Build (sheb, sh-multilib-linux-musl, -mb)	14s
Build (x86_32, x86_64-multilib-linux-musl, -m32)	15s
Build (x86_64, x86_64-multilib-linux-musl)	19s
	4m 21s

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