Do not build external plugins by default

source/Makefile.mk

@@ -781,11 +781,10 @@ endif
 # ---------------------------------------------------------------------------------------------------------------------
 # Check if we should build the external plugins
 
+ifeq ($(EXTERNAL_PLUGINS),true)
 ifneq ($(DEBUG),true)
 ifneq ($(TESTBUILD),true)
 ifneq (,$(wildcard $(CWD)/native-plugins/external/Makefile.mk))
-EXTERNAL_PLUGINS = true
-ifeq ($(EXTERNAL_PLUGINS),true)
 BASE_FLAGS += -DHAVE_EXTERNAL_PLUGINS
 include $(CWD)/native-plugins/external/Makefile.mk
 endif