bug#41142: [PATCH] GUILE_PKG bails out when 'pkg-config' is missing

* meta/guile.m4 (GUILE_PKG): Ensure that 'pkg-config' is available. Use
AC_REQUIRE for PKG_PROG_PKG_CONFIG to avoid unnecessary invocations.
---
 meta/guile.m4 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/meta/guile.m4 b/meta/guile.m4
index bc0daaf46..508f8b9d4 100644
--- a/meta/guile.m4
+++ b/meta/guile.m4
@@ -60,7 +60,10 @@
 # @code{AC_SUBST}.
 #
 AC_DEFUN([GUILE_PKG],
- [PKG_PROG_PKG_CONFIG
+ [AC_REQUIRE([PKG_PROG_PKG_CONFIG])
+  if test "x$PKG_CONFIG" = x; then
+    AC_MSG_ERROR(["Missing pkg-config"])
+  fi
   _guile_versions_to_search="m4_default([$1], [3.0 2.2 2.0])"
   if test -n "$GUILE_EFFECTIVE_VERSION"; then
     _guile_tmp=""
-- 
2.20.1