make: treat packages like modules when it comes to linking

Makefile.include

@@ -236,7 +236,6 @@ endif
 
 # the binaries to link
 BASELIBS += $(BINDIR)${APPLICATION}.a
-BASELIBS += $(USEPKG:%=${BINDIR}%.a)
 BASELIBS += $(APPDEPS)
 
 .PHONY: all clean flash term doc debug debug-server reset objdump help info-modules

Makefile.modules

@@ -3,7 +3,7 @@ USEMODULE := $(filter-out $(filter-out $(FEATURES_PROVIDED), $(FEATURES_OPTIONAL
 ED = $(addprefix FEATURE_,$(sort $(filter $(FEATURES_PROVIDED), $(FEATURES_REQUIRED))))
 ED += $(addprefix MODULE_,$(sort $(USEMODULE) $(USEPKG)))
 EXTDEFINES = $(addprefix -D,$(shell echo '$(ED)' | tr 'a-z-' 'A-Z_'))
-REALMODULES = $(filter-out $(PSEUDOMODULES), $(sort $(USEMODULE)))
+REALMODULES = $(filter-out $(PSEUDOMODULES), $(sort $(USEMODULE) $(USEPKG)))
 export BASELIBS += $(REALMODULES:%=$(BINDIR)%.a)
 
 CFLAGS += $(EXTDEFINES)