Try fix

Author: mcbarton

cmake/modules/GoogleTest.cmake

@@ -39,6 +39,8 @@ ExternalProject_Add(
   #            -DCMAKE_ARCHIVE_OUTPUT_DIRECTORY_RELEASE:PATH=ReleaseLibs
   #            -Dgtest_force_shared_crt=ON
   CONFIGURE_COMMAND ${config_cmd} -G ${CMAKE_GENERATOR}
+  		          -S ${CMAKE_BINARY_DIR}/unittests/googletest-prefix/src/googletest/
+		            -B ${CMAKE_BINARY_DIR}/unittests/googletest-prefix/src/googletest-build/
                 -DCMAKE_BUILD_TYPE=$<CONFIG>
                 -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
                 -DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}