Add additional controls for forcing serialization and blocking.

Move HIP_COHERENT_HOST_ALLOC so it is read once at init time.
Add HIP_LAUNCH_BLOCKING_KERNELS, HIP_API_BLOCKING.
Update docs on debug and chicken bits.

Conflicts:
	src/hip_hcc.cpp


[ROCm/hip commit: ff2f54c1bf]

projects/hip/src/hip_module.cpp

@@ -333,7 +333,7 @@ hipError_t hipModuleLaunchKernel(hipFunction_t f,
 #endif // USE_DISPATCH_HSA_KERNEL
 
 
-        ihipPostLaunchKernel(hStream, lp);
+        ihipPostLaunchKernel(f->_kernelName, hStream, lp);
 
     }