Fix: remove hexdump references

Author: stuartherbert

config.m4

@@ -1,15 +1,15 @@
 dnl $Id$
-dnl config.m4 for extension hexdump
+dnl config.m4 for extension xxhash
 
 dnl Comments in this file start with the string 'dnl'.
 dnl Remove where necessary. This file will not work
 dnl without editing.
 
 dnl If your extension references something external, use with:
 
-dnl PHP_ARG_WITH(hexdump, for hexdump support,
+dnl PHP_ARG_WITH(xxhash, for xxhash support,
 dnl Make sure that the comment is aligned:
-dnl [  --with-hexdump             Include hexdump support])
+dnl [  --with-xxhash             Include xxhash support])
 
 dnl Otherwise use enable: