pgsql: Blindly try to fix MSVC build's use of genbki.pl andGen_fmgrtab

Blindly try to fix MSVC build's use of genbki.pl and Gen_fmgrtab.pl.

We need to use a stamp file to record the runs of these scripts, as
is done on the Unix side.  I think I got it right, but can't test.

While at it, extend this handmade dependency logic to also check the
generating script files, as the makefiles do.

Discussion: https://postgr.es/m/16925.1525376229@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/bad51a49a4c0ee2dd87191f8aea5ca839c9dbf15

Modified Files
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src/tools/msvc/Solution.pm | 66 +++++++++++++++++++++++++++++-----------------
src/tools/msvc/clean.bat   |  4 ++-
2 files changed, 45 insertions(+), 25 deletions(-)