Check pkg-config exit status when configuring (Bug#10626).

* configure.in (PKG_CHECK_MODULES): Do not assume that pkg-config
works; check its exit status.  Problem reported by Jordi Gutiérrez
Hermoso in
<http://lists.gnu.org/archive/html/emacs-devel/2012-01/msg00787.html>.

ChangeLog

+2012-04-07  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Check pkg-config exit status when configuring (Bug#10626).
+	* configure.in (PKG_CHECK_MODULES): Do not assume that pkg-config
+	works; check its exit status.  Problem reported by Jordi Gutiérrez
+	Hermoso in
+	<http://lists.gnu.org/archive/html/emacs-devel/2012-01/msg00787.html>.
+
 2012-04-07  Glenn Morris  <rgm@gnu.org>
 
 	* README, configure.in (AC_INIT): Bump version to 24.1.50.

configure.in

@@ -1124,17 +1124,14 @@ AC_DEFUN([PKG_CHECK_MODULES], [
      if $PKG_CONFIG --atleast-pkgconfig-version $PKG_CONFIG_MIN_VERSION; then
         AC_MSG_CHECKING(for $2)
 
-        if $PKG_CONFIG --exists "$2" 2>&AS_MESSAGE_LOG_FD; then
-            AC_MSG_RESULT(yes)
-            succeeded=yes
-
-            AC_MSG_CHECKING($1_CFLAGS)
-            $1_CFLAGS=`$PKG_CONFIG --cflags "$2"|sed -e 's,///*,/,g'`
-            AC_MSG_RESULT($$1_CFLAGS)
+        if $PKG_CONFIG --exists "$2" 2>&AS_MESSAGE_LOG_FD &&
+	   $1_CFLAGS=`$PKG_CONFIG --cflags "$2" 2>&AS_MESSAGE_LOG_FD` &&
+	   $1_LIBS=`$PKG_CONFIG --libs "$2" 2>&AS_MESSAGE_LOG_FD`; then
 
-            AC_MSG_CHECKING($1_LIBS)
-            $1_LIBS=`$PKG_CONFIG --libs "$2"|sed -e 's,///*,/,g'`
-            AC_MSG_RESULT($$1_LIBS)
+	    $1_CFLAGS=`AS_ECHO(["$$1_CFLAGS"]) | sed -e 's,///*,/,g'`
+	    $1_LIBS=`AS_ECHO(["$$1_LIBS"]) | sed -e 's,///*,/,g'`
+            AC_MSG_RESULT([yes CFLAGS='$$1_CFLAGS' LIBS='$$1_LIBS'])
+            succeeded=yes
         else
             AC_MSG_RESULT(no)
             $1_CFLAGS=""