Remove some special cases from MSVC build scripts

Remove some special cases from MSVC build scripts

Here we add additional parsing of Makefiles to determine when to add
references to libpgport and libpgcommon.  We also remove the need for
adding the current contrib_extrasource by adding sine very basic logic to
implement the Makefile rules which add .l and .y files when they exist for
a given .o file in the Makefile.

This is just some very basic additional parsing of Makefiles to try to
keep things more consistent between builds using make and MSVC builds.
This happens to work with how our current Makefiles are laid out, but it
could easily be broken in the future if someone chooses do something in
the Makefile that we don't have parsing support for.  We will cross that
bridge when we come to it.

Author: David Rowley
Discussion: https://postgr.es/m/CAApHDvoPULi5JW3933NxgwxOmu9Ncvpcyt87UhEHAUX16QqmpA@mail.gmail.com