ponyc

Split PR workflow into three independent workflows #2

Job	Run time
arm Linux glibc	1s
armhf Linux glibc	2m 16s
x86-64 Apple Darwin	1s
arm64 Linux musl	1s
arm64 Linux glibc	2m 17s
arm64 Windows MSVC	1m 35s
x86-64 Windows MSVC	1s
arm64 Apple Darwin	2m 25s
x86-64 Linux glibc	1s
x86-64 Linux musl	1s
riscv64 Linux glibc	1s
use ${{ matrix.directives }}	1s
with sanitizers ${{ matrix.directives }}	1s
	8m 42s

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