Use AM_MISSING_PROG for ragel and git

Makefile.am

@@ -28,8 +28,8 @@ CHANGELOG_RANGE =
 ChangeLog: $(srcdir)/ChangeLog
 $(srcdir)/ChangeLog:
 	$(AM_V_GEN) if test -d "$(top_srcdir)/.git"; then \
-	  (GIT_DIR=$(top_srcdir)/.git $(top_srcdir)/missing --run \
-	   git log $(CHANGELOG_RANGE) --stat) | fmt --split-only > $@.tmp \
+	  (GIT_DIR=$(top_srcdir)/.git \
+	   $(GIT) log $(CHANGELOG_RANGE) --stat) | fmt --split-only > $@.tmp \
 	  && mv -f $@.tmp "$(srcdir)/ChangeLog" \
 	  || ($(RM) $@.tmp; \
 	      echo Failed to generate ChangeLog, your ChangeLog may be outdated >&2; \

configure.ac

@@ -23,6 +23,8 @@ AC_PROG_CC
 AM_PROG_CC_C_O
 AC_PROG_CXX
 PKG_PROG_PKG_CONFIG([0.20])
+AM_MISSING_PROG([RAGEL], [ragel])
+AM_MISSING_PROG([GIT], [git])
 
 # Version
 m4_define(hb_version_triplet,m4_split(AC_PACKAGE_VERSION,[[.]]))

src/Makefile.am

@@ -302,7 +302,7 @@ EXTRA_DIST += \
 	hb-ot-shape-complex-sea-machine.rl \
 	$(NULL)
 .rl.hh:
-	$(AM_V_GEN)$(top_srcdir)/missing --run ragel -e -F1 -o "$@.tmp" "$<" && \
+	$(AM_V_GEN)$(RAGEL) -e -F1 -o "$@.tmp" "$<" && \
 	mv "$@.tmp" "$@" || ( $(RM) "$@.tmp" && false )
 
 noinst_PROGRAMS = \