Make Documenation depend on headers_install

Cc: rdunlap@infradead.org
Cc: linux-doc@vger.kernel.org
Cc: sudeep.dutt@intel.com
Cc: nikhil.rao@intel.com
Cc: ashutosh.dixit@intel.com
Cc: akpm@linux-foundation.org
Cc: gregkh@linuxfoundation.org
Signed-off-by: NPeter Foley <pefoley2@pefoley.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Makefile

@@ -1532,6 +1532,8 @@ endif
 	$(cmd_crmodverdir)
 	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \
 	$(build)=$(build-dir)
+# Make sure the latest headers are built for Documentation
+Documentation/: headers_install
 %/: prepare scripts FORCE
 	$(cmd_crmodverdir)
 	$(Q)$(MAKE) KBUILD_MODULES=$(if $(CONFIG_MODULES),1) \