Makefile: Add subdir dependency on config-devices-all.mak

What 23bf49b really seemed to try to
fix is that Makefile could recurse into *-softmmu/ subdirectories before
a new *-softmmu/config-devices.mak was generated from pci.mak.

Fix this by adding a dependency on config-all-devices.mak, which in turn
has dependencies on *-softmmu/config-devices.mak.

Reported-by: Gerhard Wiesinger <lists@wiesinger.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

Makefile

@@ -123,6 +123,9 @@ qemu-options.def: $(SRC_PATH)/qemu-options.hx
 	$(call quiet-command,sh $(SRC_PATH)/scripts/hxtool -h < $< > $@,"  GEN   $@")
 
 SUBDIR_RULES=$(patsubst %,subdir-%, $(TARGET_DIRS))
+SOFTMMU_SUBDIR_RULES=$(filter %-softmmu,$(SUBDIR_RULES))
+
+$(SOFTMMU_SUBDIR_RULES): config-all-devices.mak
 
 subdir-%:
 	$(call quiet-command,$(MAKE) $(SUBDIR_MAKEFLAGS) -C $* V="$(V)" TARGET_DIR="$*/" all,)