gpl: fix CUDA flags

without `-fopenmp` Kokkos raises an error if it was built with OpenMP support

Signed-off-by: Igor Sokolov <disk.destroyer@yahoo.com>

Author: Igor Sokolov

src/gpl/CMakeLists.txt

@@ -13,6 +13,7 @@ find_package(ortools REQUIRED)
 find_package(LEMON NAMES LEMON lemon REQUIRED)
 find_package(OpenMP REQUIRED)
 
+
 message(STATUS "Found OR-Tools: ${ortools_DIR} (version: ${ortools_VERSION})")
 
 swig_lib(NAME      gpl
@@ -112,10 +113,15 @@ if(ENABLE_GPU)
   # but the CXX flag is also harmless on the existing CPU TUs.
   target_compile_options(gpl_lib PRIVATE
     $<$<COMPILE_LANGUAGE:CXX>:-ffp-contract=off>
-    $<$<COMPILE_LANGUAGE:CUDA>:--fmad=false>
+    $<$<COMPILE_LANGUAGE:CUDA>:--fmad=false --extended-lambda>
     $<$<COMPILE_LANGUAGE:HIP>:-ffp-contract=off>
   )
   target_link_libraries(gpl_lib Kokkos::kokkos KokkosFFT::fft)
+  if (Kokkos_ENABLE_OPENMP)
+    target_compile_options(gpl_lib PRIVATE
+      $<$<COMPILE_LANGUAGE:CUDA>:-fopenmp>
+    )
+  endif()
   if(Kokkos_ENABLE_CUDA)
     # cuda runtime symbols are referenced from the CUDA TU; expose cudart
     # so that gpl_lib (and the openroad binary) link against libcudart.