ir_constant_expression: Support scalar * vector and scalar * matrix.

The test here is slightly different since we need to keep matrix
multiplication separate.

Fixes piglit tests const-vec-scalar-03.frag and const-mat-scalar-03.frag.
diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
index 2fab03b..e039504 100644
--- a/src/glsl/ir_constant_expression.cpp
+++ b/src/glsl/ir_constant_expression.cpp
@@ -362,25 +362,28 @@
 
       break;
    case ir_binop_mul:
-      if (ir->operands[0]->type == ir->operands[1]->type &&
-	  !ir->operands[0]->type->is_matrix()) {
-	 for (c = 0; c < ir->operands[0]->type->components(); c++) {
+      if ((op[0]->type == op[1]->type && !op[0]->type->is_matrix())
+	  || op0_scalar || op1_scalar) {
+	 for (unsigned c = 0, c0 = 0, c1 = 0;
+	      c < components;
+	      c0 += c0_inc, c1 += c1_inc, c++) {
+
 	    switch (ir->operands[0]->type->base_type) {
 	    case GLSL_TYPE_UINT:
-	       data.u[c] = op[0]->value.u[c] * op[1]->value.u[c];
+	       data.u[c] = op[0]->value.u[c0] * op[1]->value.u[c1];
 	       break;
 	    case GLSL_TYPE_INT:
-	       data.i[c] = op[0]->value.i[c] * op[1]->value.i[c];
+	       data.i[c] = op[0]->value.i[c0] * op[1]->value.i[c1];
 	       break;
 	    case GLSL_TYPE_FLOAT:
-	       data.f[c] = op[0]->value.f[c] * op[1]->value.f[c];
+	       data.f[c] = op[0]->value.f[c0] * op[1]->value.f[c1];
 	       break;
 	    default:
 	       assert(0);
 	    }
 	 }
       } else
-	 /* FINISHME: Support operations with non-equal types. */
+	 /* FINISHME: Support vector/matrix and matrix multiplication. */
 	 return;
 
       break;