the linker flags for x86_64 builds. adjusted accordingly.
- build_cross_osx.sh, build_cross_win32.sh, build_cross_win64.sh:
added the cross-compile scripts I have been using.
- Makefiles,other: added LDFLAGS variables for future use.
git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@704 af15c1b1-3010-417e-b628-4374ebc0bcbd
