Only build and install VST plugin if backend is available

Makefile

@@ -740,6 +740,7 @@ endif
 
 ifeq ($(LINUX),true)
 ifeq ($(HAVE_X11),true)
+ifeq ($(HAVE_PYQT),true)
 	# Install vst plugin
 	install -d $(DESTDIR)$(LIBDIR)/vst/carla.vst
 
@@ -762,6 +763,7 @@ ifeq ($(HAVE_X11),true)
 	rm -rf $(DESTDIR)$(LIBDIR)/vst/carla.vst/styles
 	$(LINK) $(LIBDIR)/carla/styles $(DESTDIR)$(LIBDIR)/vst/carla.vst/styles
 endif
+endif
 endif
 
 	# --------------------------------------------------------------------------------------------------------------------

source/plugin/Makefile

@@ -108,6 +108,7 @@ TARGETS = \
 
 ifeq ($(LINUX),true)
 ifeq ($(HAVE_X11),true)
+ifeq ($(HAVE_PYQT),true)
 TARGETS += \
 	$(BINDIR)/CarlaRack$(LIB_EXT) \
 	$(BINDIR)/CarlaRackFX$(LIB_EXT) \
@@ -116,6 +117,7 @@ TARGETS += \
 	$(BINDIR)/CarlaPatchbayFX$(LIB_EXT)
 endif
 endif
+endif
 
 # ----------------------------------------------------------------------------------------------------------------------------