add a target to print out 80-column violations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36032 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Makefile.rules b/Makefile.rules
index de97781..723fefc 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -1725,6 +1725,9 @@
 endif
 endif
 
+check-line-length:
+	@egrep '.{81}' $(Sources)
+
 #------------------------------------------------------------------------
 # Print out the directories used for building
 #------------------------------------------------------------------------