* Fix hipcc for hip-clang.
If there is -g, do not add -O3 by default.
If HIP_VDI_HOME is not set, set HIP_VDI_HOME based on hipcc directory for HIP/VDI runtime.
For HIP/VDI runtime, set HIP_CLANG_PATH and DEVICE_LIB_PATH based on HIP_VDI_HOME only if they exist.
This allows using HIP/VDI runtime with hip-clang installed at /opt/rocm/llvm and device lib installed
at /opt/rocm/lib.
* Fix HIP_VDI_HOME for hipcc called from /opt/rocm/bin
Yaxun (Sam) Liu
e17f94e080