[PATCH v2] Makefile: Fix config-devices.mak not regenerated when Kconfig updated

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

When hw/$DIR/Kconfig is changed, the corresponding generated
hw/$DIR/config-devices.mak is not being updated.
Fix this by including all the hw/*/Kconfig files to the prerequisite
names of the rule generating the config-devices.mak files.

Fixes: e0e312f3525a (build: switch to Kconfig)
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v2:
Simplify using the wildcard() function instead of calling `sed` (danpb)

You can see this tread where Peter reported the failure:
https://lists.gnu.org/archive/html/qemu-devel/2019-11/msg00125.html

How to reproduce:

  $ git checkout branch_modifying_kconfig
  $ make i386-softmmu/all
  $ make clean
  $ git checkout prev_branch
  $ make clean
  $ make i386-softmmu/all
    # error

If OK, I plan to include this fix in the "hw/i386/pc: Split PIIX3
southbridge from i440FX northbridge" pull request.
---
 Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 0e994a275d..f4fca08cd7 100644
--- a/Makefile
+++ b/Makefile
@@ -384,7 +384,8 @@ MINIKCONF_ARGS = \
     CONFIG_LINUX=$(CONFIG_LINUX) \
     CONFIG_PVRDMA=$(CONFIG_PVRDMA)
 
-MINIKCONF_INPUTS = $(SRC_PATH)/Kconfig.host $(SRC_PATH)/hw/Kconfig
+MINIKCONF_INPUTS = $(SRC_PATH)/Kconfig.host $(SRC_PATH)/hw/Kconfig \
+                   $(wildcard $(SRC_PATH)/hw/*/Kconfig)
 MINIKCONF = $(PYTHON) $(SRC_PATH)/scripts/minikconf.py \
 
 $(SUBDIR_DEVICES_MAK): %/config-devices.mak: default-configs/%.mak $(MINIKCONF_INPUTS) $(BUILD_DIR)/config-host.mak
-- 
2.21.0