clang/gcc: Add build option FREECAD_WARN_ERROR to force to make warnings into errors

src/Mod/Drawing/App/CMakeLists.txt

@@ -67,6 +67,9 @@ endif(FREECAD_USE_PCH)
 
 add_library(Drawing SHARED ${Drawing_SRCS} ${Features_SRCS} ${DrawingAlgos_SRCS})
 target_link_libraries(Drawing ${Drawing_LIBS})
+if (FREECAD_WARN_ERROR)
+    target_compile_warn_error(Drawing)
+endif()
 
 SET_BIN_DIR(Drawing Drawing /Mod/Drawing)
 SET_PYTHON_PREFIX_SUFFIX(Drawing)

src/Mod/Drawing/Gui/CMakeLists.txt

@@ -83,6 +83,9 @@ SET(DrawingGuiIcon_SVG
 add_library(DrawingGui SHARED ${DrawingGui_SRCS} ${DrawingGuiView_SRCS}
                               ${DrawingGuiViewProvider_SRCS} ${DrawingGuiIcon_SVG})
 target_link_libraries(DrawingGui ${DrawingGui_LIBS})
+if (FREECAD_WARN_ERROR)
+    target_compile_warn_error(DrawingGui)
+endif()
 
 
 SET_BIN_DIR(DrawingGui DrawingGui /Mod/Drawing)