kbuild: Call depmod.sh via shell

The script has the executable bit in git, but plain old patch(1) can't
create executable files.
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Michal Marek <mmarek@suse.cz>

Makefile

@@ -1526,7 +1526,8 @@ quiet_cmd_rmfiles = $(if $(wildcard $(rm-files)),CLEAN   $(wildcard $(rm-files))
 
 # Run depmod only if we have System.map and depmod is executable
 quiet_cmd_depmod = DEPMOD  $(KERNELRELEASE)
-      cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE)
+      cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
+                   $(KERNELRELEASE)
 
 # Create temporary dir for module support files
 # clean it up only when building all modules