v3d: Add Compute Shader compilation support.

While waiting for the CSD UABI to get reviewed, I keep having to rebase
the CS patch.  Just land the compiler side for now to keep it from
diverging.

For now this covers just GLES 3.1 compute shaders, not CL kernels.

src/broadcom/compiler/v3d_compiler.h

@@ -691,6 +691,12 @@ struct v3d_fs_prog_data {
         bool uses_center_w;
 };
 
+struct v3d_compute_prog_data {
+        struct v3d_prog_data base;
+        /* Size in bytes of the workgroup's shared space. */
+        uint32_t shared_size;
+};
+
 static inline bool
 vir_has_uniform(struct qinst *inst)
 {