legal-info: add hash for our own license file

This silences the annoying warning that there is no hash file for our
own COPYING file.

Also change the message so that it is more obvious what we're doing.

Reported-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

Makefile

@@ -744,8 +744,8 @@ legal-info-clean:
 
 .PHONY: legal-info-prepare
 legal-info-prepare: $(LEGAL_INFO_DIR)
-	@$(call MESSAGE,"Collecting legal info")
-	@$(call legal-license-file,buildroot,buildroot,.,COPYING,COPYING,HOST)
+	@$(call MESSAGE,"Buildroot $(BR2_VERSION_FULL) Collecting legal info")
+	@$(call legal-license-file,buildroot,buildroot,support/legal-info,COPYING,COPYING,HOST)
 	@$(call legal-manifest,PACKAGE,VERSION,LICENSE,LICENSE FILES,SOURCE ARCHIVE,SOURCE SITE,TARGET)
 	@$(call legal-manifest,PACKAGE,VERSION,LICENSE,LICENSE FILES,SOURCE ARCHIVE,SOURCE SITE,HOST)
 	@$(call legal-manifest,buildroot,$(BR2_VERSION_FULL),GPL-2.0+,COPYING,not saved,not saved,HOST)

support/legal-info/buildroot.hash

@@ -0,0 +1,2 @@
+# Locally computed
+sha256 9755181e27175cb3510b4da8629caa406fb355a19aa8e7d55f06bf8ab33323c4  COPYING