Enhance .gitignore, svn:ingore and svn:global-ignores

 - Ignore working directories (and the flavored versions)
 - Ignore Makefile.local files
 - Synchronize the ignored files/directories between git and subversion

NOTE: it was intentional to _not_ ignore .git and .svn directories in
subversion and git respectively, as a dual checkout of the Ports tree is
not supported.

Approved by:		portmgr (mat)
Differential Revision:	https://reviews.freebsd.org/D10698

.gitignore

@@ -1,6 +1,8 @@
 /distfiles
 /packages
+/*/*/Makefile.local
 /*/*/work
+/*/*/work-*
 /INDEX-[0-9]*
 *~
 *.rej