Improve revision.inc regeneration program

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23994 3ad0048d-3df7-0310-abae-a5850022a9f2
 Avoid failure in exported directories

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23995 3ad0048d-3df7-0310-abae-a5850022a9f2
 Regenerated Makefile and revision.inc

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@23996 3ad0048d-3df7-0310-abae-a5850022a9f2