cmake

Fix warnings when directly including yyjson.c: #177 #449

Job	Run time
linux_archs (i386)	1m 26s
linux_opts (gcc, no_fp)	33s
linux_archs (arm32v7)	13m 54s
codecov	50s
linux_opts (gcc, no_reader)	25s
fuzzing	5m 20s
linux_archs (arm64v8)	15m 20s
linux_opts (gcc, no_writer)	35s
linux_archs (ppc64le)	12m 39s
linux_checks (Debug, Default, Valgrind)	1m 6s
linux_clang_latest	1m 19s
linux_opts (gcc, no_utf8)	1m 4s
linux_checks (Debug, Default, Sanitizer)	1m 19s
linux_archs (s390x)	12m 59s
linux_checks (Debug, ReduceBinary, Valgrind)	55s
linux_opts (clang, no_fp)	34s
linux_archs (riscv64)	12m 53s
linux_gcc_latest	1m 35s
linux_checks (Debug, ReduceBinary, Sanitizer)	40s
linux_opts (clang, no_reader)	27s
linux_checks (Release, Default, Valgrind)	1m 21s
linux_opts (clang, no_writer)	33s
linux_checks (Release, Default, Sanitizer)	1m 24s
linux_gcc4	47s
linux_opts (clang, no_utf8)	45s
linux_gcc5_i386	1m 20s
linux_checks (Release, ReduceBinary, Valgrind)	1m 4s
linux_checks (Release, ReduceBinary, Sanitizer)	1m 1s
linux_tinycc	23s
linux_checks (MinSizeRel, Default, Valgrind)	1m 8s
macos_clang	29s
linux_checks (MinSizeRel, Default, Sanitizer)	1m 24s
windows_msvc	1m 49s
linux_checks (MinSizeRel, ReduceBinary, Valgrind)	58s
linux_checks (MinSizeRel, ReduceBinary, Sanitizer)	53s
	1h 41m 12s

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