pgsql: Have initdb display relative paths to start postmaster if used to

Log Message:
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Have initdb display relative paths to start postmaster if used to invoke
initdb, and display in a path-native way.

Modified Files:
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pgsql/src/bin/initdb:
initdb.c (r1.68 -> r1.69)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/initdb/initdb.c.diff?r1=1.68&r2=1.69)