#2070 Solaris LP64 build incorrectly hardcodes /usr/openwin/lib

[Tim Mooney]

Whether or not one specifies --enable-64bit when
configuring tk 8.4.13, tk always hardcodes
-R/usr/openwin/lib into both libtk-8.4.so and wish.

I believe that's wrong when building for LP64 Solaris
(e.g. generating ELF64 objects) -- if it's going to
hardcode anything it should be -R/usr/openwin/lib/64.

This type of thing no doubt applies to other multi-ABI
platforms too (e.g. IRIX vs. IRIX64).