Allow local and sync db to be treated separately

Allow local and sync db to be treated separately

Implement this seemingly simple change in package.h:

 typedef enum _pmpkgfrom_t {
-       PKG_FROM_CACHE = 1,
-       PKG_FROM_FILE
+       PKG_FROM_FILE = 1,
+       PKG_FROM_LOCALDB,
+       PKG_FROM_SYNCDB
 } pmpkgfrom_t;

which requires flushing out several assumptions from around the codebase
with regards to usage of the PKG_FROM_CACHE value. Make some changes where
required to allow the switch, and now the correct value should be set (via a
crude hack) depending on whether a package was loaded as an entry in a local
db or a sync db.

This patch underwent some big rebasing from Allan and Dan.

Signed-off-by: Dan McGee <dan@archlinux.org>
Signed-off-by: Allan McRae <allan@archlinux.org>