compare characters in brace expressions using proper case folding #714

Job	Run time
macos (tiny, macos-12)	1m 12s
macos (tiny, macos-14)	55s
windows (HUGE, msvc, no, no, x64, stable)	7m 7s
macos (normal, macos-12)	6m 14s
linux (tiny, clang, native)	2m 9s
windows (HUGE, mingw, yes, yes, x86, stable, yes)	9m 33s
macos (normal, macos-14)	4m 26s
linux (tiny, gcc, native)	1m 53s
windows (HUGE, msvc, no, yes, x86)	12m 45s
windows (HUGE, mingw, yes, no, x64, yes)	10m 2s
linux (normal, clang, native)	5m 53s
macos (huge, macos-12)	14m 45s
linux (normal, gcc, native)	6m 30s
windows (NORMAL, msvc, yes, no, x86)	7m 46s
macos (huge, macos-14)	14m 35s
windows (NORMAL, mingw, no, yes, x64)	9m 6s
linux (huge, clang, native)	9m 6s
windows (TINY, msvc, yes, yes, x64)	1m 54s
linux (huge, gcc, native)	11m 24s
windows (TINY, mingw, no, no, x86)	2m 22s
linux (tiny, clang, nogui)	1m 33s
linux (tiny, gcc, nogui)	1m 45s
linux (normal, gcc, i386, ./src/shadow)	5m 50s
linux (huge, gcc, uchar, testgui, true, dynamic)	9m 36s
linux (huge, clang, asan, 5.1)	17m 12s
linux (huge, gcc, unittests, true)	3m 12s
linux (normal, gcc, vimtags)	3m 44s
	3h 2m 29s

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