devlink, rdma, tipc: properly define TARGETS without HAVE_MNL

Leaving a variable with a generic name such as TARGETS undefined would lead
to Make picking up its value from the environment. Avoid this by always
defining TARGETS in the Makefiles.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

devlink/Makefile

@@ -1,10 +1,12 @@
 # SPDX-License-Identifier: GPL-2.0
 include ../config.mk
 
+TARGETS :=
+
 ifeq ($(HAVE_MNL),y)
 
 DEVLINKOBJ = devlink.o mnlg.o
-TARGETS=devlink
+TARGETS += devlink
 
 CFLAGS += $(shell $(PKG_CONFIG) libmnl --cflags)
 LDLIBS += $(shell $(PKG_CONFIG) libmnl --libs)

rdma/Makefile

@@ -1,11 +1,13 @@
 # SPDX-License-Identifier: GPL-2.0
 include ../config.mk
 
+TARGETS :=
+
 ifeq ($(HAVE_MNL),y)
 
 RDMA_OBJ = rdma.o utils.o dev.o link.o
 
-TARGETS=rdma
+TARGETS += rdma
 endif
 
 all:	$(TARGETS) $(LIBS)

tipc/Makefile

@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 include ../config.mk
 
+TARGETS :=
+
 ifeq ($(HAVE_MNL),y)
 
 TIPCOBJ=bearer.o \
@@ -10,7 +12,7 @@ TIPCOBJ=bearer.o \
     node.o socket.o \
     peer.o tipc.o
 
-TARGETS=tipc
+TARGETS += tipc
 
 endif