CMake improvements.

- Directed tests build hip_hcc as subdir.
- Support HCC_HOME env var to control which HCC to use for build
  hip_hcc.

tests/src/CMakeLists.txt

@@ -40,12 +40,12 @@ if (${HIP_PLATFORM} STREQUAL "hcc")
 	#Include HIP and HC since the tests need both of these:
 	#Note below HSA path is surgically included only where necessary.
 	include_directories(${HIP_PATH}/include)
-        include_directories(${HSA_PATH}/include)
-	# hip_hcc.o:
-    #add_library(hip_hcc STATIC ${HIP_PATH}/src/hip_hcc.cpp )
-    add_library(hip_hcc STATIC ${HIP_PATH}/src/hip_hcc.cpp ${HIP_PATH}/src/staging_buffer.cpp)
-    target_include_directories(hip_hcc PRIVATE ${HSA_PATH}/include ${CODEXL_SDK_ATAL_PATH}/include)
+    include_directories(${HSA_PATH}/include)
 
+    # This will create a subdir "hip_hcc" in the test build directory
+    # Any changes to hip_hcc source will be detected and force the library and then the tests to be rebuilt.  
+    add_subdirectory(${HIP_PATH} hip_hcc)
+    link_directories(${CMAKE_CURRENT_BINARY_DIR}/hip_hcc)  # search the local hip_hcc for libhip_hcc.a
 
 elseif (${HIP_PLATFORM} STREQUAL "nvcc")
 	MESSAGE ("HIP_PLATFORM=nvcc")
@@ -71,7 +71,7 @@ add_library(test_common OBJECT test_common.cpp )
 macro (make_hip_executable exe cpp)  
     if (${HIP_PLATFORM} STREQUAL "hcc")
         add_executable (${exe} ${cpp} ${ARGN} $<TARGET_OBJECTS:test_common> )
-#        target_link_libraries(${exe} hip_hcc)
+        target_link_libraries(${exe} hip_hcc)
     else()
         add_executable (${exe} ${cpp} ${ARGN} $<TARGET_OBJECTS:test_common> )
     endif()