mesa: Dynamically allocate the storage for program local parameters.

mesa: Dynamically allocate the storage for program local parameters.

The array was 64kb per struct gl_program, plus we statically stored a copy
of one on disk for _mesa_DummyProgram.  Given that most struct gl_programs
we generate are for GLSL shaders that don't have local parameters, this
was a waste.

Since you can store and fetch parameters beyond what the program actually
uses, we do have to do a late allocation if necessary at
GetProgramLocalParameter time.

Reduces peak memory usage in the dota2 trace I made by 76MB (4.5%)

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>