Define __HIPCC__ flag at compile time when using HIPCC on HCC path

Change-Id: I5e967e0e2327264d5d3b0ca705c2504fcd33d75e

bin/hipcc

@@ -92,7 +92,7 @@ if ($HIP_PLATFORM eq "hcc") {
 
     # HCC* may be used to compile src/hip_hcc.o (and also feed the HIPCXXFLAGS below)
     $HCC = "$HCC_HOME/bin/hcc";
-    $HCCFLAGS = "-hc -I$HCC_HOME/include ";
+    $HCCFLAGS = "-hc  -D__HIPCC__ -I$HCC_HOME/include ";
 
     $HIPCC=$HCC;
     $HIPCXXFLAGS = $HCCFLAGS;