FindOpenMP: Simplify explicit "omp" library checks

For toolchains that do not provide a builtin `omp` library the compiler
driver's OpenMP flag should not be needed when linking.  We also do not
need the compiler driver's verbose flag because we are not parsing its
output.

Modules/FindOpenMP.cmake

@@ -336,8 +336,8 @@ function(_OPENMP_GET_FLAGS LANG FLAG_MODE OPENMP_FLAG_VAR OPENMP_LIB_NAMES_VAR)
         try_compile( OpenMP_COMPILE_RESULT_${FLAG_MODE}_${OPENMP_PLAIN_FLAG}
           SOURCE_FROM_VAR "${_OPENMP_TEST_SRC_NAME}" _OPENMP_TEST_SRC_CONTENT
           LOG_DESCRIPTION "Trying ${LANG} OpenMP compiler with '${OpenMP_libomp_LIBRARY}'"
-          CMAKE_FLAGS "-DCOMPILE_DEFINITIONS:STRING=${OPENMP_FLAGS_TEST}"
-          LINK_LIBRARIES ${CMAKE_${LANG}_VERBOSE_FLAG} ${OpenMP_libomp_LIBRARY}
+          COMPILE_DEFINITIONS ${OPENMP_FLAG}
+          LINK_LIBRARIES ${OpenMP_libomp_LIBRARY}
         )
         if(NOT OpenMP_COMPILE_RESULT_${FLAG_MODE}_${OPENMP_PLAIN_FLAG})
           find_path(OpenMP_${LANG}_INCLUDE_DIR omp.h)
@@ -347,9 +347,9 @@ function(_OPENMP_GET_FLAGS LANG FLAG_MODE OPENMP_FLAG_VAR OPENMP_LIB_NAMES_VAR)
             try_compile( OpenMP_COMPILE_RESULT_${FLAG_MODE}_${OPENMP_PLAIN_FLAG}
               SOURCE_FROM_VAR "${_OPENMP_TEST_SRC_NAME}" _OPENMP_TEST_SRC_CONTENT
               LOG_DESCRIPTION "Trying ${LANG} OpenMP compiler with '${OpenMP_libomp_LIBRARY}' and '${OpenMP_${LANG}_INCLUDE_DIR}'"
-              CMAKE_FLAGS "-DCOMPILE_DEFINITIONS:STRING=${OPENMP_FLAGS_TEST}"
-                          "-DINCLUDE_DIRECTORIES:STRING=${OpenMP_${LANG}_INCLUDE_DIR}"
-              LINK_LIBRARIES ${CMAKE_${LANG}_VERBOSE_FLAG} ${OpenMP_libomp_LIBRARY}
+              CMAKE_FLAGS "-DINCLUDE_DIRECTORIES:STRING=${OpenMP_${LANG}_INCLUDE_DIR}"
+              COMPILE_DEFINITIONS ${OPENMP_FLAG}
+              LINK_LIBRARIES ${OpenMP_libomp_LIBRARY}
             )
           endif()
         endif()
@@ -370,8 +370,8 @@ function(_OPENMP_GET_FLAGS LANG FLAG_MODE OPENMP_FLAG_VAR OPENMP_LIB_NAMES_VAR)
         try_compile( OpenMP_COMPILE_RESULT_${FLAG_MODE}_${OPENMP_PLAIN_FLAG}
           SOURCE_FROM_VAR "${_OPENMP_TEST_SRC_NAME}" _OPENMP_TEST_SRC_CONTENT
           LOG_DESCRIPTION "Trying ${LANG} OpenMP compiler with '${OpenMP_libomp_LIBRARY}'"
-          CMAKE_FLAGS "-DCOMPILE_DEFINITIONS:STRING=${OPENMP_FLAGS_TEST}"
-          LINK_LIBRARIES ${CMAKE_${LANG}_VERBOSE_FLAG} ${OpenMP_libomp_LIBRARY}
+          COMPILE_DEFINITIONS ${OPENMP_FLAG}
+          LINK_LIBRARIES ${OpenMP_libomp_LIBRARY}
         )
         if(OpenMP_COMPILE_RESULT_${FLAG_MODE}_${OPENMP_PLAIN_FLAG})
           set("${OPENMP_FLAG_VAR}" "${OPENMP_FLAG}" PARENT_SCOPE)