check for m4 version in buildconf

CHANGES

@@ -6,6 +6,10 @@
 
                                   Changelog
 
+Daniel (15 March 2004)
+- buildconf now checks the m4 version too, since autoconf requires a GNU m4
+  version to build proper configure scripts.
+
 Daniel (12 March 2004)
 - Added CURLOPT_POSTFIELDSIZE_LARGE, the large file version of
   CURLOPT_POSTFIELDSIZE to allow POSTs larger than 2GB.