debian/bin/gencontrol.py: Add rules to build debian/build/config.*

It is no longer possible to run the "setup" rules without a compiler,
because Kconfig symbols can depend on compiler properties.  Add a way
to invoke just the first step of setup, which merges the kconfig files
and overrides together.

debian/bin/gencontrol.py

@@ -580,6 +580,12 @@ class Gencontrol(Base):
         makefile.add('setup_%s_%s_%s_real' % (arch, featureset, flavour),
                      cmds=cmds_setup)
 
+        merged_config = ('debian/build/config.%s_%s_%s' %
+                         (arch, featureset, flavour))
+        makefile.add(merged_config,
+                     cmds=["$(MAKE) -f debian/rules.real %s %s" %
+                           (merged_config, makeflags)])
+
         # Substitute kernel version etc. into maintainer scripts,
         # translations and lintian overrides
         self._substitute_file('headers.postinst', vars,

debian/changelog

@@ -14,6 +14,7 @@ linux (4.19.20-2) UNRELEASED; urgency=medium
   * udeb: Move basic PV modules from {hyperv,virtio}-modules to kernel-image
   * udeb: Move drivers from {hyperv,virtio}-modules to
     {fb,input,nic,scsi}-modules
+  * debian/bin/gencontrol.py: Add rules to build debian/build/config.*
 
   [ Wookey ]
   * linux-perf: Enable coresight trace (libopencsd) support in perf