(backport) Make "-index" example more illustrative #4621

Job	Run time
gcc	10m 18s
gcc (--disable-shared)	10m 47s
gcc (--enable-symbols)	10m 33s
gcc (--enable-symbols=mem)	11m 13s
gcc (--enable-symbols=all)	11m 28s
msvc	9m 16s
msvc (OPTS=static,msvcrt)	9m 26s
msvc (OPTS=static,staticpkg,msvcrt)	9m 55s
msvc (OPTS=symbols)	10m 8s
msvc (OPTS=symbols STATS=compdbg,memdbg)	10m 41s
	1h 43m 45s

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