c-ctype, regex, verify: port to gcc -std=c90 -pedantic

c-ctype, regex, verify: port to gcc -std=c90 -pedantic

Avoid constructions that are rejected by gcc -std=c90 -pedantic.
This fixes a porting bug I recently reintroduced in regex, and
some other instances that I discovered while testing the fix.
* lib/c-ctype.h [__STRICT_ANSI__]: Avoid ({ ... }).
* lib/regcomp.c (utf8_sb_map) [__STRICT_ANSI__]: Avoid [0 ... N] = E.
* lib/regex_internal.h [!_LIBC && GNULIB_LOCK]: Do not use a macro
with an empty argument if this is a pedantic pre-C99 GCC.
* lib/verify.h: Do not use _Static_assert if this is a pedantic
pre-C11 GCC.