Fix void* arithmetic.

GCC allows arithmetic on void* treating void as char.  Clang and
the language spec does not.

Change-Id: I939f2432f276979bb81881406e10528597ac6001

runtime/hsa-runtime/core/runtime/amd_blit_sdma.cpp

@@ -455,8 +455,8 @@ hsa_status_t BlitSdma<RingIndexTy, HwIndexMonotonic, SizeToCountOffset>::SubmitC
     hsa_dim3_t Doff = *dst_offset;
     hsa_dim3_t Range = *range;
 
-    Src.base += Soff.z * Src.slice + Soff.y * Src.pitch;
-    Dst.base += Doff.z * Dst.slice + Doff.y * Dst.pitch;
+    Src.base = static_cast<char*>(Src.base) + Soff.z * Src.slice + Soff.y * Src.pitch;
+    Dst.base = static_cast<char*>(Dst.base) + Doff.z * Dst.slice + Doff.y * Dst.pitch;
     Soff.y = Soff.z = 0;
     Doff.y = Doff.z = 0;