Fix quoting for CONFIG-related sed expression.
diff --git a/configure.ac b/configure.ac
index 5e93a5d..4c20259 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,7 +43,7 @@
 
 dnl ============================================================================
 
-CONFIG=`echo ${ac_configure_args} | sed -e "s#\'\([^ ]*\)\'#\1#g"`
+CONFIG=`echo ${ac_configure_args} | sed -e 's#'"'"'\([^ ]*\)'"'"'#\1#g'`
 AC_SUBST([CONFIG])
 
 dnl Library revision.