Merge branch 'ab/compat-regex'

Merge branch 'ab/compat-regex'

* ab/compat-regex:
  Fix compat/regex ANSIfication on MinGW
  autoconf: regex library detection typofix
  autoconf: don't use platform regex if it lacks REG_STARTEND
  t/t7008-grep-binary.sh: un-TODO a test that needs REG_STARTEND
  compat/regex: get rid of old-style definition
  compat/regex: define out variables only used under RE_ENABLE_I18N
  Change regerror() declaration from K&R style to ANSI C (C89)
  compat/regex: get the gawk regex engine to compile within git
  compat/regex: use the regex engine from gawk for compat

Conflicts:
	compat/regex/regex.c