sparse: ignore warning from new glibc headers

With at least glibc 2.39, glibc provides a function declaration that matches with this POSIX interface: int regexec(const regex_t *restrict preg, const char *restrict string, size_t nmatch, regmatch_t pmatch[restrict], int eflags); such prototype requires variable-length-array for `pmatch'. Thus, sparse reports this error: > ../add-patch.c: note: in included file (through ../git-compat-util.h): > /usr/include/regex.h:682:41: error: undefined identifier '__nmatch' > /usr/include/regex.h:682:41: error: bad constant expression type > /usr/include/regex.h:682:41: error: Variable length array is used. Note: `__nmatch' is POSIX's nmatch. The glibc's intention is informing their users to provides a large enough buffer to hold `__nmatch' results and provides diagnosis if necessary. It's merely a glibc' implementation detail. Hide that usage from sparse by using standard C11's macro: __STDC_NO_VLA__ Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>