compare characters in brace expressions using proper case folding #715

Job	Run time
macos (tiny, macos-12)	1m 4s
macos (tiny, macos-14)	39s
windows (HUGE, msvc, no, no, x64, stable)	8m 53s
macos (normal, macos-12)	6m 21s
windows (HUGE, mingw, yes, yes, x86, stable, yes)	9m 47s
macos (normal, macos-14)	4m 26s
linux (tiny, clang, native)	2m 4s
windows (HUGE, msvc, no, yes, x86)	13m 4s
linux (tiny, gcc, native)	1m 57s
windows (HUGE, mingw, yes, no, x64, yes)	9m 51s
linux (normal, clang, native)	5m 4s
macos (huge, macos-12)	15m 25s
windows (NORMAL, msvc, yes, no, x86)	6m 37s
linux (normal, gcc, native)	5m 20s
macos (huge, macos-14)	13m 22s
windows (NORMAL, mingw, no, yes, x64)	9m 28s
linux (huge, clang, native)	9m 10s
windows (TINY, msvc, yes, yes, x64)	1m 33s
linux (huge, gcc, native)	4m 11s
windows (TINY, mingw, no, no, x86)	2m 37s
linux (tiny, clang, nogui)	1m 39s
linux (tiny, gcc, nogui)	1m 39s
linux (normal, gcc, i386, ./src/shadow)	5m 49s
linux (huge, gcc, uchar, testgui, true, dynamic)	9m 3s
linux (huge, clang, asan, 5.1)	16m 30s
linux (huge, gcc, unittests, true)	2m 38s
linux (normal, gcc, vimtags)	2m 6s
	2h 50m 17s

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