Fix build with hip-clang.

- Add necessary function attribute for HIP programming model.
- Explicitly include hsa headers.

src/include/devcomm.h

@@ -12,7 +12,7 @@
 #include <stdint.h>
 
 // Convert volatile access to atomic
-#if defined(__HIP_PLATFORM_HCC__) || defined(__HCC__)
+#if defined(__HIP_PLATFORM_HCC__) || defined(__HCC__) || defined(__HIPCC__)
 #define LOAD(VAR) __atomic_load_n((VAR), __ATOMIC_SEQ_CST)
 #define STORE(DST, SRC) __atomic_store_n((DST), (SRC), __ATOMIC_SEQ_CST)
 #else