Update README.md

[ROCm/roctracer commit: 1bceac618b]

projects/roctracer/README.md

@@ -33,7 +33,6 @@ The library source tree:
 
  - Set environment:
   export HIP_PATH=<your path>/HIP
-  export HCC_PATH=<your path>/hcc
   export HCC_HOME=<your path>/hcc/build
   export CMAKE_PREFIX_PATH=/opt/rocm/lib:/opt/rocm/include/hsa