pgsql: Make sure -D is an absolute path when starting server on Windows

Make sure -D is an absolute path when starting server on Windows.

This is needed because Windows services may get started with a different
current directory than where pg_ctl is executed.  We want relative -D
paths to be interpreted relative to pg_ctl's CWD, similarly to what
happens on other platforms.

In support of this, move the backend's make_absolute_path() function
into src/port/path.c (where it probably should have been long since)
and get rid of the rather inferior version in pg_regress.

Kumar Rajeev Rastogi, reviewed by MauMau

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/9aca51250681d2e8d18ed1d73e7cd1283d1cf303

Modified Files
--------------
src/backend/utils/init/miscinit.c |   71 ------------------------
src/bin/pg_ctl/pg_ctl.c           |   14 ++++-
src/include/miscadmin.h           |    1 -
src/include/port.h                |    1 +
src/port/path.c                   |  111 ++++++++++++++++++++++++++++++++++++-
src/test/regress/pg_regress.c     |   27 ---------
6 files changed, 124 insertions(+), 101 deletions(-)