Makefile: allow for extra flags necessary when compiling for SDL3

examples/Makefile

@@ -265,9 +265,9 @@ endif
 # Define include paths for required headers: INCLUDE_PATHS
 # NOTE: Some external/extras libraries could be required (stb, easings...)
 #------------------------------------------------------------------------------------------------
-INCLUDE_PATHS = -I. -I$(RAYLIB_PATH)/src -I$(RAYLIB_PATH)/src/external
-
+INCLUDE_PATHS = -I. -I$(RAYLIB_PATH)/src -I$(RAYLIB_PATH)/src/external $(EXTRA_INCLUDE_PATHS)
 # Define additional directories containing required header files
+
 ifeq ($(TARGET_PLATFORM),PLATFORM_DESKTOP_GLFW)
     ifeq ($(PLATFORM_OS),BSD)
         INCLUDE_PATHS += -I$(RAYLIB_INCLUDE_PATH) -I/usr/pkg/include -I/usr/X11R7/include

src/Makefile

@@ -462,7 +462,7 @@ CFLAGS += $(CUSTOM_CFLAGS)
 # Define include paths for required headers: INCLUDE_PATHS
 # NOTE: Several external required libraries (stb and others)
 #------------------------------------------------------------------------------------------------
-INCLUDE_PATHS = -I.
+INCLUDE_PATHS = -I. $(EXTRA_INCLUDE_PATHS)
 
 # Define additional directories containing required header files
 ifeq ($(TARGET_PLATFORM),PLATFORM_DESKTOP_GLFW)