svn path=/branches/BRANCH_6-3/; revision=5187
Fixes BerliOS Bug #13207 (reported + fix suggested by Terry Brown).
# CHANGES:
+* autoconf 2.60 is now required to build fetchmail; it uses
+ AC_USE_SYSTEM_EXTENSIONS to replace AC_AIX, AC_MINIX, and the like.
* Removed dead FETCHMAIL_DEBUG code from fetchmail.h that was disabled by
default with no switches in configure to enable it. However, the macro would
have been prone to a symlink attack. Found by Nico Golde.