update_mir_test_checks: Improve the check for LLVM IR in MIR files

The LLVM IR section of a MIR document can start with "--- |" rather
than just "---", because "|" is a sigil for a freeform document in
YAML. We need to handle this so that we don't try to add check lines
to the LLVM IR functions in a MIR file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323178 91177308-0d34-0410-b5e6-96231b3b80d8

utils/update_mir_test_checks.py

diff --git a/utils/update_mir_test_checks.py b/utils/update_mir_test_checks.py
index 3756af1..068c418 100755
--- a/utils/update_mir_test_checks.py
+++ b/utils/update_mir_test_checks.py
@@ -360,7 +360,7 @@
             if m:
                 state = 'ir function prefix'
                 func_name = m.group('func')
-            if input_line.strip() == '---':
+            if input_line.rstrip('| \r\n') == '---':
                 state = 'document'
             output_lines.append(input_line)
         elif state == 'document':