Small change to silence compiler warnings about casing pointer to object to a pointer to function like this
.../llvm/projects/openmp/libomptarget/src/omptarget.cpp: In member function 'void RTLsTy::LoadRTLs()':
.../llvm/projects/openmp/libomptarget/src/omptarget.cpp:318:57: warning: ISO C++ forbids casting between pointer-to-function and pointer-to-object [-Wpedantic]
dynlib_handle, "__tgt_rtl_is_valid_binary"))) ^