ktest: Add IGNORE_WARNINGS to ignore warnings in some patches

Doing a patchcheck test, there may be warnings that gcc produces which
may be OK, and the test should not fail on that commit. By adding a
IGNORE_WARNINGS option to list a space delimited SHA1s that are ignored
lets the user avoid having the test fail on certain commits.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/tools/testing/ktest/sample.conf b/tools/testing/ktest/sample.conf
index e2d8d83..82c966c 100644
--- a/tools/testing/ktest/sample.conf
+++ b/tools/testing/ktest/sample.conf
@@ -604,7 +604,12 @@
 #      build, boot, test.
 #
 #   Note, the build test will look for warnings, if a warning occurred
-#     in a file that a commit touches, the build will fail.
+#     in a file that a commit touches, the build will fail, unless
+#     IGNORE_WARNINGS is set for the given commit's sha1
+#
+#   IGNORE_WARNINGS can be used to disable the failure of patchcheck
+#     on a particuler commit (SHA1). You can add more than one commit
+#     by adding a list of SHA1s that are space delimited.
 #
 #   If BUILD_NOCLEAN is set, then make mrproper will not be run on
 #   any of the builds, just like all other TEST_TYPE tests. But
@@ -619,6 +624,7 @@
 #   PATCHCHECK_TYPE = boot
 #   PATCHCHECK_START = 747e94ae3d1b4c9bf5380e569f614eb9040b79e7
 #   PATCHCHECK_END = HEAD~2
+#   IGNORE_WARNINGS = 42f9c6b69b54946ffc0515f57d01dc7f5c0e4712 0c17ca2c7187f431d8ffc79e81addc730f33d128
 #
 #
 #