add encode_heap_oop_not_null for riscv #273

Job	Run time
Select platforms	1s
linux-x64-hs-nopch / build (debug)	58s
linux-x64 / build (debug)	45s
linux-x64 / build (release)	57s
linux-x64-hs-minimal / build (debug)	59s
linux-cross-compile / build (aarch64)	57s
linux-cross-compile / build (arm)	58s
linux-cross-compile / build (s390x)	55s
linux-x64-hs-optimized / build (debug)	59s
linux-cross-compile / build (ppc64le)	58s
linux-cross-compile / build (riscv64)	53s
docs / build (debug)	59s
linux-x64-hs-zero / build (debug)	58s
linux-x86 / build (debug)	56s
linux-x86 / build (release)	56s
macos-aarch64 / build (debug)	47s
macos-aarch64 / build (release)	46s
macos-x64 / build (debug)	44s
macos-x64 / build (release)	44s
windows-aarch64 / build (debug)	45s
windows-x64 / build (debug)	1s
windows-aarch64 / build (release)	10s
windows-x64 / build (release)	1s
windows-x64	1s
macos-x64	1s
macos-aarch64	1s
linux-x64	1s
linux-x86	1s
Remove bundle artifacts	4s
	17m 16s

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