Automatically enable external plugins when its repo is available

source/Makefile.mk

@@ -519,7 +519,7 @@ endif
 
 # ---------------------------------------------------------------------------------------------------------------------
 
-ifeq ($(EXTERNAL_PLUGINS),true)
+ifneq (,$(wildcard $(CWD)/native-plugins/external/Makefile.mk))
 BASE_FLAGS += -DHAVE_EXTERNAL_PLUGINS
 include $(CWD)/native-plugins/external/Makefile.mk
 endif

source/native-plugins/Makefile

@@ -6,7 +6,6 @@
 
 CWD=..
 CWDE=..
-EXTERNAL=external/
 MODULENAME=native-plugins
 include ../modules/Makefile.mk
 
@@ -53,7 +52,7 @@ OBJS_all = \
 # ---------------------------------------------------------------------------------------------------------------------
 # Include external plugins, if present
 
-ifeq ($(EXTERNAL_PLUGINS),true)
+ifneq (,$(wildcard external/Makefile))
 include external/Makefile
 endif