Fix test on Windows by telling diff to ignore Windows-specific line endings. (llvm#158297)

Should fix bot: https://lab.llvm.org/buildbot/#/builders/46/builds/23206

(cherry picked from commit b0cb4e1)

Author: dyung

llvm/utils/lit/tests/diff-test-update.py

@@ -8,13 +8,13 @@
 
 # RUN: not %{lit} --update-tests -v %S/Inputs/diff-test-update | FileCheck %s
 
-# RUN: diff %S/Inputs/diff-test-update/single-split-file.out %S/Inputs/diff-test-update/single-split-file.test
-# RUN: diff %S/Inputs/diff-test-update/single-split-file.out %S/Inputs/diff-test-update/single-split-file-populated.test
-# RUN: diff %S/Inputs/diff-test-update/multiple-split-file.out %S/Inputs/diff-test-update/multiple-split-file.test
-# RUN: diff %S/Inputs/diff-test-update/multiple-split-file.out %S/Inputs/diff-test-update/multiple-split-file-populated.test
-# RUN: diff %S/Inputs/diff-test-update/single-split-file-no-expected.out %S/Inputs/diff-test-update/single-split-file-no-expected.test
-# RUN: diff %S/Inputs/diff-test-update/split-c-comments.out %S/Inputs/diff-test-update/split-c-comments.test
-# RUN: diff %S/Inputs/diff-test-update/split-whitespace.out "%S/Inputs/diff-test-update/split whitespace.test"
+# RUN: diff --strip-trailing-cr %S/Inputs/diff-test-update/single-split-file.out %S/Inputs/diff-test-update/single-split-file.test
+# RUN: diff --strip-trailing-cr %S/Inputs/diff-test-update/single-split-file.out %S/Inputs/diff-test-update/single-split-file-populated.test
+# RUN: diff --strip-trailing-cr %S/Inputs/diff-test-update/multiple-split-file.out %S/Inputs/diff-test-update/multiple-split-file.test
+# RUN: diff --strip-trailing-cr %S/Inputs/diff-test-update/multiple-split-file.out %S/Inputs/diff-test-update/multiple-split-file-populated.test
+# RUN: diff --strip-trailing-cr %S/Inputs/diff-test-update/single-split-file-no-expected.out %S/Inputs/diff-test-update/single-split-file-no-expected.test
+# RUN: diff --strip-trailing-cr %S/Inputs/diff-test-update/split-c-comments.out %S/Inputs/diff-test-update/split-c-comments.test
+# RUN: diff --strip-trailing-cr %S/Inputs/diff-test-update/split-whitespace.out "%S/Inputs/diff-test-update/split whitespace.test"
 
 
 # CHECK: # update-diff-test: could not deduce source and target from {{.*}}1.in and {{.*}}2.in