pgsql: Create a script to handle stamping release version numbers into

Log Message:
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Create a script to handle stamping release version numbers into files,
replacing the tedious and error-prone manual process we've been using.

Tags:
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REL7_4_STABLE

Modified Files:
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pgsql/src/tools:
RELEASE_CHANGES (r1.40.4.1 -> r1.40.4.2)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/tools/RELEASE_CHANGES?r1=1.40.4.1&r2=1.40.4.2)

Added Files:
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pgsql/src/tools:
version_stamp.pl (r1.1.10.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/tools/version_stamp.pl?rev=1.1.10.1&content-type=text/x-cvsweb-markup)