At the moment, support for runtime debug output using the OMPTARGET_DEBUG=1 environment variable is only available with CMAKE_BUILD_TYPE=Debug builds. The patch allows setting it independently using the LIBOMPTARGET_ENABLE_DEBUG option, which is enabled by default depending on CMAKE_BUILD_TYPE. That is, unless this option is set explicitly, nothing changes. This is the same mechanism used by LLVM for LLVM_ENABLE_ASSERTIONS.
This patch also remove adding -g -O0 in debug builds, it should be handled by cmake.
Idea by @hfinkel