Remove __attribute((overloadable)) from rsUnpackColor8888.

Change-Id: I12e8af774a0a61bd8571c31406894779a443c300
diff --git a/lib/Renderscript/runtime/rs_core.c b/lib/Renderscript/runtime/rs_core.c
index 102289a..f0c9490 100644
--- a/lib/Renderscript/runtime/rs_core.c
+++ b/lib/Renderscript/runtime/rs_core.c
@@ -45,7 +45,7 @@
 }
 */
 
-extern float4 __attribute__((overloadable)) rsUnpackColor8888(uchar4 c)
+extern float4 rsUnpackColor8888(uchar4 c)
 {
     return convert_float4(c) * 0.003921569f;
 }