[OverloadCompilerFlags] add EXTRA_CXXFLAGS just in case...

cmake/modules/OverloadCompilerFlags.cmake

@@ -81,6 +81,7 @@ macro(finalize_compiler_script)
     set( COMPILER_SCRIPT_FILE "${COMPILER_SCRIPT_FILE}\n# store flags\nFLAGS=\"\$@\"")
     set( COMPILER_SCRIPT_FILE "${COMPILER_SCRIPT_FILE}\nMAKE_EXECUTABLE_NEW=0\n")
     set( COMPILER_SCRIPT_FILE "${COMPILER_SCRIPT_FILE}\nif [ \"\$CXXFLAGS\" == \"\" ]; then\n  # default CXX flags\n  CXXFLAGS=\"${DEFAULT_CXXFLAGS}\"\nfi\n")
+    set( COMPILER_SCRIPT_FILE "${COMPILER_SCRIPT_FILE}\nif [ \"\$EXTRA_CXXFLAGS\" != \"\" ]; then\n  # extra CXX flags\n  CXXFLAGS=\"$CXXFLAGS $EXTRA_CXXFLAGS\"\nfi\n")
     set( COMPILER_SCRIPT_FILE "${COMPILER_SCRIPT_FILE}\nGRIDS=\nCONFIG_H=${CMAKE_BINARY_DIR}/config.h")
     set( COMPILER_SCRIPT_FILE "${COMPILER_SCRIPT_FILE}\nif [ \"\$GRIDTYPE\" != \"\" ]; then")
     set( COMPILER_SCRIPT_FILE "${COMPILER_SCRIPT_FILE}\n  GRIDS=`\$GREP \"defined USED_[A-Z_]*_GRIDTYPE\" \$CONFIG_H | \$SED 's/\\(.*defined USED\\_\\)\\(.*\\)\\(\\_GRIDTYPE*\\)/\\2/g'`\nfi\n")