pgsql: Make restricted_exec feature for Windows more robust by using

Log Message:
-----------

Make restricted_exec feature for Windows more robust by using the environment
to pass the flag instead of the command line - some implementations of
getopt fail if getopt arguments are present after non-getopt arguments.

Modified Files:
--------------
    pgsql/src/bin/initdb:
        initdb.c (r1.111 -> r1.112)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/initdb/initdb.c.diff?r1=1.111&r2=1.112)