Ensure that parallel parsing sbs calls pass on --no-depend-generate and --no-depend-include (as these influence makefile generation). Make .DEFAULT a double-colon target, so we don't have to worry about duplicate instances due to -include. Code review updates.

NOTESRC_RELEASER
Symbian Software Ltd. (kits.notify@symbian.com)

NOTESRC_RELEASE_REASON
Symbian Build System release.