Makefile: try to get gbuild-to-ide running on the internal python3

Or we could just hold our breath until Apple adds python3 to macOS.

Change-Id: I94dd054be8a28490fd86b72092a4389194ca785f
Reviewed-on: https://gerrit.libreoffice.org/32047Reviewed-by: jan iversen <jani@documentfoundation.org>
Tested-by: jan iversen <jani@documentfoundation.org>
Reviewed-by: Björn Michaelsen <bjoern.michaelsen@canonical.com>

Makefile.in

@@ -405,8 +405,10 @@ dump-deps-sort:
 	@$(SRCDIR)/bin/module-deps.pl -t $(MAKE) $(SRCDIR)/Makefile.gbuild
 
 define gb_Top_GbuildToIdeIntegration
-$(1)-ide-integration: gbuildtojson
-	cd $(SRCDIR) && $(SRCDIR)/bin/gbuild-to-ide --ide $(1) --make $(MAKE)
+$(1)-ide-integration: gbuildtojson $(if $(filter MACOSX,$(OS_FOR_BUILD)),python3.all)
+	cd $(SRCDIR) && \
+		$(if $(filter MACOSX,$(OS_FOR_BUILD)),PATH="$(INSTROOT_FOR_BUILD)/Frameworks/LibreOfficePython.framework/Versions/Current/bin:$(PATH)") \
+		$(SRCDIR)/bin/gbuild-to-ide --ide $(1) --make $(MAKE)
 
 endef