Apply patch for Debian from Samuel Thibault.

aclocal.m4

@@ -8114,7 +8114,7 @@ $$1_PKG_ERRORS
 Consider adjusting the PKG_CONFIG_PATH environment variable if you
 installed software in a non-standard prefix.
 
-_PKG_TEXT])dnl
+_PKG_TEXT])[]dnl
         ])
 elif test $pkg_failed = untried; then
      	AC_MSG_RESULT([no])
@@ -8125,7 +8125,7 @@ path to pkg-config.
 
 _PKG_TEXT
 
-To get pkg-config, see <http://pkg-config.freedesktop.org/>.])dnl
+To get pkg-config, see <http://pkg-config.freedesktop.org/>.])[]dnl
         ])
 else
 	$1[]_CFLAGS=$pkg_cv_[]$1[]_CFLAGS