This patch adds tests for bug 23007, strtod ignoring any sign in the
input string in the case of a NaN result.
Tested for x86_64.
[BZ #23007]
* stdlib/tst-strtod-nan-sign-main.c: New file.
* stdlib/tst-strtod-nan-sign.c: Likewise.
* wcsmbs/tst-wcstod-nan-sign.c: Likewise.
* stdlib/Makefile (tests): Add tst-strtod-nan-sign.
($(objpfx)tst-strtod-nan-sign): Depend on $(libm).
* wcsmbs/Makefile (tests) Add tst-wcstod-nan-sign.
($(objpfx)tst-wcstod-nan-sign): Depend on $(libm).