remove jenkins.mk, buildserver does not use it anylonger.

jenkins.mk

-
-all:
-	@echo "Available make-targets:"
-	@echo "gluonbranch:                        show the gluon branch site.mk requires"
-	@echo "                                    ex: \$> make -f jenkins.mk gluonbranch"
-	@echo "                                    # v2016.1.4"
-	@echo "targets:                            show enabled gluon targets aka SOC models to build freifunk firmware for."
-	@echo "                                    This requires the current working directory being the gluon source tree."
-	@echo "                                    ex: \$> cd <gluon-src-tree>; make -f <path to site-conf>/jenkins.mk targets"
-
-# gluonbranch
-ifeq ($(MAKECMDGOALS),gluonbranch)
-
-include site.mk
-
-.PHONY: gluonbranch
-gluonbranch:
-	@echo $(GLUON_CHECKOUT)
-endif
-
-# targets
-ifeq ($(MAKECMDGOALS),targets)
-
-GLUONDIR:=${CURDIR}
-include $(GLUONDIR)/include/gluon.mk
-include $(GLUONDIR)/targets/targets.mk
-
-.PHONY: targets
-targets:
-	@echo $(GLUON_TARGETS)
-endif