nv30, nv40: non-trivially unify nv[34]0_fragprog.c

nv30, nv40: non-trivially unify nv[34]0_fragprog.c

The files are mostly the same except:
1. On NV40, some TGSI instructions are emulated with several hardware ones
2. Some instructions such as DDX/DDY, and STR were missing from nv30
3. NV40 has more sophisticated register management

nv30 now supports all instructions and uses the nv40 register management.