[gcr] build: Check lcov and genhtml in configure

[Daiki Ueno <dueno src gnome org>]

commit 21622b91f5fd3161f124aab7ade3547558ba7be0
Author: Daiki Ueno <dueno src gnome org>
Date:   Fri Jun 15 06:14:46 2018 +0200

    build: Check lcov and genhtml in configure

 configure.ac | 10 ++++++++++
 1 file changed, 10 insertions(+)
---
diff --git a/configure.ac b/configure.ac
index 06dfc0c..d08a50d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -350,6 +350,16 @@ if test "$enable_coverage" = "yes"; then
                AC_MSG_ERROR(gcov tool is not available)
        fi
 
+       AC_PATH_PROG(LCOV, lcov, no)
+       if test "$LCOV" = "no" ; then
+               AC_MSG_ERROR(lcov tool is not installed)
+       fi
+
+       AC_PATH_PROG(GENHTML, genhtml, no)
+       if test "$GENHTML" = "no" ; then
+               AC_MSG_ERROR(lcov's genhtml tool is not installed)
+       fi
+
        CFLAGS="$CFLAGS -O0 -g --coverage"
        LDFLAGS="$LDFLAGS --coverage"
 fi