ARB prog: Change handling of program parameter limits

ARB prog: Change handling of program parameter limits

Several changes are made to program parameter limits.  Several of the
non-NATIVE limits are set higher.  All of the NATIVE limits are set to
zero in the core Mesa code.  Each driver must set the actual value in
its context creation routine.  If the NATIVE value remains zero, this
indicates that hardware shaders may not be supported.

Each of the preceeding changes matches the bahavior of Apple's shader
assembler, so it seems safe.

Finally, we limit the value of MaxEnvParams to be no greater than
MaxNativeAttribs.  At least one case has been found where an
application does the wrong thing if MaxNativeAttribs < MaxEnvParams.

See also bugzilla #23490.