Makefile: improve `make check` usefulness

Silence the make echo'ing, so the output is cleaner.

Add an exit code to check_whence.py, so we can get a real failure for
bad WHENCE files.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

Makefile

@@ -6,7 +6,7 @@ FIRMWAREDIR = /lib/firmware
 all:
 
 check:
-	./check_whence.py
+	@./check_whence.py
 
 install:
 	mkdir -p $(DESTDIR)$(FIRMWAREDIR)

check_whence.py

@@ -33,6 +33,7 @@ def list_git():
             yield line.rstrip('\n')
 
 def main():
+    ret = 0
     whence_list = list(list_whence())
     known_files = set(name for name in whence_list if not name.endswith('/')) | \
                   set(['check_whence.py', 'configure', 'Makefile',
@@ -42,6 +43,7 @@ def main():
 
     for name in sorted(list(known_files - git_files)):
         sys.stderr.write('E: %s listed in WHENCE does not exist\n' % name)
+        ret = 1
 
     for name in sorted(list(git_files - known_files)):
         # Ignore subdirectory changelogs and GPG detached signatures
@@ -55,6 +57,8 @@ def main():
                 break
         else:
             sys.stderr.write('E: %s not listed in WHENCE\n' % name)
+            ret = 1
+    return ret
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())