Teach FileCheck to handle trailing CHECK-NOT patterns.

A CHECK-NOT pattern without a following CHECK pattern simply checks that the
pattern doesn't match before the end of the input file.

You can even have only CHECK-NOT patterns to check that strings appear nowhere
in the input file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116592 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CommandGuide/FileCheck.pod b/docs/CommandGuide/FileCheck.pod
index 433979a..8a8eddf 100644
--- a/docs/CommandGuide/FileCheck.pod
+++ b/docs/CommandGuide/FileCheck.pod
@@ -165,7 +165,7 @@
 =head2 The "CHECK-NOT:" directive
 
 The CHECK-NOT: directive is used to verify that a string doesn't occur
-between two matches (or the first match and the beginning of the file).  For
+between two matches (or before the first match, or after the last match).  For
 example, to verify that a load is removed by a transformation, a test like this
 can be used: