client build on Windows impossible due to absolute paths

The cronbuilds >7.0.17837 of DynamoRIO are shipped with a broken CMake integration: When building a DR client with this version, CMake tries to locate locate the dbghelp_imports.lib at the absolute path C:/projects/dynamorio/<...> instead of the relative one. This obviously does not work on machines other than the one DR is compiled and packaged on.

These pathes are generated by DR during the packaging and can be found in: Dynamorio-7.0.x-0/cmake/DynamoRIOTarget64.cmake