Enhance RGBASM warning diagnostics: #2961

Job	Run time
macos-static	2m 0s
windows-mingw-build (32)	1m 3s
unix (ubuntu-20.04, g++, make)	5m 14s
windows-mingw-build (64)	1m 0s
windows (32, windows-2019)	5m 26s
unix (ubuntu-20.04, g++, cmake)	5m 23s
windows (32, windows-2022)	5m 42s
unix (ubuntu-20.04, clang++, make)	6m 4s
windows (64, windows-2019)	4m 46s
unix (ubuntu-20.04, clang++, cmake)	6m 1s
windows (64, windows-2022)	4m 42s
unix (ubuntu-22.04, g++, make)	5m 29s
unix (ubuntu-22.04, g++, cmake)	5m 49s
unix (ubuntu-22.04, clang++, make)	3m 58s
unix (ubuntu-22.04, clang++, cmake)	3m 54s
unix (macos-14, clang++, make)	6m 37s
unix (macos-14, clang++, cmake)	5m 39s
windows-mingw-testing (windows-2019, 32)	3m 55s
windows-mingw-testing (windows-2019, 64)	4m 17s
windows-mingw-testing (windows-2022, 32)	4m 20s
windows-mingw-testing (windows-2022, 64)	3m 59s
	1h 35m 18s

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