pgsql: Set up ar, dlltool, dllwrap, and windres for cross-compiling if

Log Message:
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Set up ar, dlltool, dllwrap, and windres for cross-compiling if necessary.
Plus some makefile cleanup.

part of a patch from Richard Evans

Modified Files:
--------------
pgsql:
configure (r1.615 -> r1.616)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure?r1=1.615&r2=1.616)
configure.in (r1.575 -> r1.576)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure.in?r1=1.575&r2=1.576)
pgsql/src:
Makefile.global.in (r1.247 -> r1.248)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/Makefile.global.in?r1=1.247&r2=1.248)
pgsql/src/bin/pgevent:
Makefile (r1.10 -> r1.11)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pgevent/Makefile?r1=1.10&r2=1.11)
pgsql/src/interfaces/libpq:
Makefile (r1.170 -> r1.171)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/Makefile?r1=1.170&r2=1.171)
pgsql/src/makefiles:
Makefile.win32 (r1.11 -> r1.12)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/makefiles/Makefile.win32?r1=1.11&r2=1.12)