pgsql: Combine win32 and unix latch implementations.

Combine win32 and unix latch implementations.

Previously latches for windows and unix had been implemented in
different files. A later patch introduce an expanded wait
infrastructure, keeping the implementation separate would introduce too
much duplication.

This basically just moves the functions, without too much change. The
reason to keep this separate is that it allows blame to continue working
a little less badly; and to make review a tiny bit easier.

Discussion: 20160114143931.GG10941@awork2.anarazel.de

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/72e2d21c1249b674496f97cd6009c0bda62f6b4d

Modified Files
--------------
configure                        |  10 +-
configure.in                     |   8 -
src/backend/Makefile             |   3 +-
src/backend/port/.gitignore      |   1 -
src/backend/port/Makefile        |   2 +-
src/backend/port/unix_latch.c    | 731 ----------------------------
src/backend/port/win32_latch.c   | 349 --------------
src/backend/storage/ipc/Makefile |   5 +-
src/backend/storage/ipc/latch.c  | 993 +++++++++++++++++++++++++++++++++++++++
src/include/storage/latch.h      |   2 +-
src/tools/msvc/Mkvcbuild.pm      |   2 -
11 files changed, 1000 insertions(+), 1106 deletions(-)