Refactor directed test infrastructue.

- Add hierarchy.  Tests now live in directories, each with its own
  CMakeFiles.txt.  Reduces merge conflicts.
- Change make_hip_executable -> build_hip_executable.
- Refresh docs.
- Enable some tests that were previously built but not run.

Change-Id: I8c5de3c954400bf233904282b8b42861a2b7c536

tests/README.md

@@ -14,16 +14,28 @@ $ make test
 
 ### How to add a new test
 
-The tests/src/hipMemtest.cpp file contains a simple unit test and is a good starting point for other tests.  
+The tests/src/runtimeApi/memory/hipMemtest.cpp file contains a simple unit test and is a good starting point for other tests.  
 Copy this to a new test name and modify tests/src/CMakefiles.txt to add the test to the build environment.
 
+Recent versions of the test infrastructure use a hierarchy of folders.  Each folder contains src and CMakefiles.txt file. 
+See the CMakefiles.txt files for description of the intended purpose for each sub-directory.
+
+
 #### Edit CMakefiles.txt:
 // Example:
 ```
-make_hip_executable (hipMemset hipMemset.cpp) 
+# Build the test executable:
+build_hip_executable (hipMemset hipMemset.cpp) 
+
+
+# This runs the tests with the specified command-line testing.  
+# Multiple make_test may be specified.  
 make_test(hipMemset " ")
 ```
 
+It is recommended to place the build and run steps adjacent in the CMakefiles.txt.
+
+
 ### Running tests:
 ```
 ctest