PATCH: Use user-supplied LDFLAGS

Hello,

On behalf of the MacPorts project and all Mac users, I submit the following patch which allows user-specified configure-time LDFLAGS to be used:

https://trac.macports.org/browser/trunk/dports/multimedia/XviD/files/patch-LDFLAGS.diff?rev=82642

Currently the Xvid configure script allows user CFLAGS but not LDFLAGS.

Observing user LDFLAGS is important too. On Mac OS X it is desirable to be able to specify the architecture for which a program is built, and this is usually accomplished by supplying an -arch flag (e.g. "-arch i386" or "-arch x86_64") in both CFLAGS and LDFLAGS at configure time. The flag is needed at both compile time and at link time, so it needs to appear in both the CFLAGS and the LDFLAGS.

Thank you for your consideration.

-Ryan Schmidt, for the MacPorts project