glsl: reduce memory footprint of uniform_storage struct

The uniform will only be of a single type so store the data for
opaque types in a single array.

Cc: Francisco Jerez <currojerez@riseup.net>
Cc: Ilia Mirkin <imirkin@alum.mit.edu>
diff --git a/src/mesa/program/sampler.cpp b/src/mesa/program/sampler.cpp
index b1168fd..1198a3c 100644
--- a/src/mesa/program/sampler.cpp
+++ b/src/mesa/program/sampler.cpp
@@ -119,7 +119,7 @@
       return 0;
    }
 
-   if (!shader_program->UniformStorage[location].sampler[shader].active) {
+   if (!shader_program->UniformStorage[location].opaque[shader].active) {
       assert(0 && "cannot return a sampler");
       linker_error(shader_program,
 		   "cannot return a sampler named %s, because it is not "
@@ -128,7 +128,7 @@
       return 0;
    }
 
-   return shader_program->UniformStorage[location].sampler[shader].index +
+   return shader_program->UniformStorage[location].opaque[shader].index +
           getname.offset;
 }