r300/compiler: Exit immediately from rc_vert_fc() if there is an error

This way we correctly report "Too many temporaries" errors.

https://bugs.freedesktop.org/show_bug.cgi?id=48680

Note: This is a candidate for the stable branches.

src/gallium/drivers/r300/compiler/radeon_vert_fc.c

@@ -270,5 +270,9 @@ void rc_vert_fc(struct radeon_compiler *c, void *user)
 			}
 			break;
 		}
+
+		if (c->Error) {
+			return;
+		}
 	}
 }