grep: skip UTF8 checks explicitly

18547aacf5 ("grep/pcre: support utf-8", 2016-06-25) that was released with git 2.10 added the PCRE_UTF8 flag to PCRE1 matching including a call to has_non_ascii() to try to avoid breakage if there was non-utf8 encoded content in the haystack. Usually PCRE is compiled with JIT support (even if is not the default), and therefore the codepath used includes calling pcre_jit_exec, which skips UTF-8 validation by design (which might result in crashes or hangs) but when JIT support wasn't compiled we use pcre_exec instead with the posibility that grep might be aborted if invalid UTF-8 is found in the haystack. PCRE1 provides a flag since Mar 5, 2007 that could be used to skip the checks explicitly so use that to make both codepaths equivalent (the flag is ignored by pcre1_jit_exec) this fix is only implemented for PCRE1 because PCRE2 is likely to have a better solution (without the risks) instead in the future Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Helped-by: Eric Sunshine <sunshine@sunshineco.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Suggested-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>