mesa: Silence compiler warnings on Windows.
diff --git a/src/mesa/shader/prog_execute.c b/src/mesa/shader/prog_execute.c
index 4575a06..b9b7712 100644
--- a/src/mesa/shader/prog_execute.c
+++ b/src/mesa/shader/prog_execute.c
@@ -717,7 +717,7 @@
                 * result.z = result.x * APPX(result.y)
                 * We do what the ARB extension says.
                 */
-               q[2] = pow(2.0, t[0]);
+               q[2] = (GLfloat) pow(2.0, t[0]);
             }
             q[1] = t[0] - floor_t0;
             q[3] = 1.0F;