Enhance "make makepatch" to address two major deficiencies

This update to the "makepatch" target adds the following enhancements:

1. Conserves comments If the existing patch has comments, they will be transferred to the regenerated patch.

2. Supports multiple patches per file If the patch file contains concatenated patches, the makepatch target will keep these patches together. It may change the order of the patches the first time, but every time after the multi-patch will be assembled in the same order.

Behavioral changes:

A) The "old" patches are not overwritten, but rather archived at:

${WRKDIR}/makepatch-tmp/archived-patches

B) Any patch that was not replaced or renamed is deleted by makepatch

(but it is archived first, see paragraph above)

C) There regeneration messages for the user will show them which patches

are using "legacy" names formats.

D) Makepatch will do a great job at "cleaning" git patches; it removes

lines starting with "diff" and "index" in the comments section.

Notes:

E) Should a source file be modified by multiple patches (e.g. two separate

multi-patches), a composite patch will be generated.  In the above
example of two multi-patches, one would get the full patch and the
other no longer patch the source file.

Approved by: portmgr (mat)
Differential Revision: D4136