Replace USE_LOCAL_HEADERS with USE_INTERNAL_*

Makefile

@@ -207,10 +207,18 @@ ifndef USE_INTERNAL_LIBS
 USE_INTERNAL_LIBS=1
 endif
 
+ifndef USE_INTERNAL_CURL_HEADERS
+USE_INTERNAL_CURL_HEADERS=$(USE_INTERNAL_LIBS)
+endif
+
 ifndef USE_INTERNAL_OGG
 USE_INTERNAL_OGG=$(USE_INTERNAL_LIBS)
 endif
 
+ifndef USE_INTERNAL_OPENAL_HEADERS
+USE_INTERNAL_OPENAL_HEADERS=$(USE_INTERNAL_LIBS)
+endif
+
 ifndef USE_INTERNAL_VORBIS
 USE_INTERNAL_VORBIS=$(USE_INTERNAL_LIBS)
 endif
@@ -219,6 +227,10 @@ ifndef USE_INTERNAL_OPUS
 USE_INTERNAL_OPUS=$(USE_INTERNAL_LIBS)
 endif
 
+ifndef USE_INTERNAL_SDL
+USE_INTERNAL_SDL=$(USE_INTERNAL_LIBS)
+endif
+
 ifndef USE_INTERNAL_ZLIB
 USE_INTERNAL_ZLIB=$(USE_INTERNAL_LIBS)
 endif
@@ -540,7 +552,7 @@ ifeq ($(PLATFORM),darwin)
   CLIENT_LIBS += -framework IOKit
   RENDERER_LIBS += -framework OpenGL
 
-  ifeq ($(USE_LOCAL_HEADERS),1)
+  ifeq ($(USE_INTERNAL_SDL),1)
     BASE_CFLAGS += -I$(SDLHDIR)/include
 
     # We copy sdlmain before ranlib'ing it so that subversion doesn't think
@@ -697,7 +709,7 @@ ifdef MINGW
   CLIENT_LIBS += -lmingw32
   RENDERER_LIBS += -lmingw32
 
-  ifeq ($(USE_LOCAL_HEADERS),1)
+  ifeq ($(USE_INTERNAL_SDL),1)
     CLIENT_CFLAGS += -I$(SDLHDIR)/include
     ifeq ($(ARCH),x86)
     CLIENT_LIBS += $(LIBSDIR)/win32/libSDL2main.a \
@@ -1277,8 +1289,20 @@ ifdef DEFAULT_BASEDIR
   BASE_CFLAGS += -DDEFAULT_BASEDIR=\\\"$(DEFAULT_BASEDIR)\\\"
 endif
 
-ifeq ($(USE_LOCAL_HEADERS),1)
-  BASE_CFLAGS += -DUSE_LOCAL_HEADERS
+ifeq ($(USE_INTERNAL_OPENAL_HEADERS),1)
+  BASE_CFLAGS += -DUSE_INTERNAL_OPENAL_HEADERS
+endif
+
+ifeq ($(USE_INTERNAL_CURL_HEADERS),1)
+  BASE_CFLAGS += -DUSE_INTERNAL_CURL_HEADERS
+endif
+
+ifeq ($(USE_INTERNAL_SDL),1)
+  BASE_CFLAGS += -DUSE_INTERNAL_SDL_HEADERS
+endif
+
+ifeq ($(USE_INTERNAL_ZLIB),1)
+  BASE_CFLAGS += -DUSE_INTERNAL_ZLIB
 endif
 
 ifeq ($(BUILD_STANDALONE),1)