Skip padding between buildid and filenames.

[amharc]

Summary

The perf tool will left-pad the buildids to 40 characters[1] and some
buildid types supported by lld are shorter than that (e.g. md5 is only
32 characters long).

[1]
https://github.com/torvalds/linux/blob/7b58b82b86c8b65a2b57a4c6cb96a460654f9e09/tools/perf/util/dsos.c#L308

[Amir]

Please rebase the diff past 0db13e10c5645de467cc15c60f4d955bcf9b9f5d to retrigger and fix pre-merge check failure.

[amharc]

Rebase to fix test failures.

[maksfb]

LGTM. Thanks for the fix.

[maksfb]

Please add "[BOLT]" prefix to the title and drop the trailing period before the commit. Or do you want me to commit for you?

bolt/unittests/Profile/DataAggregator.cpp

TEST(DataAggregatorTest, buildID) {
   ASSERT_FALSE(DA.hasAllBuildIDs());
   FileName = DA.getFileNameForBuildID("0000");
   ASSERT_FALSE(FileName);
   FileName = DA.getFileNameForBuildID("1111");
   ASSERT_EQ(*FileName, "File1");
 
   StringRef AllValidBuildIDs = "0000 File0\n"
                                "1111 File1\n"
-                               "2222 File2\n";
+                               "2222 File2\n"
+                               "333  File3\n";
   DA.setParsingBuffer(AllValidBuildIDs);
   ASSERT_TRUE(DA.hasAllBuildIDs());
   FileName = DA.getFileNameForBuildID("1234");
   ASSERT_FALSE(FileName);
   FileName = DA.getFileNameForBuildID("2222");
   ASSERT_EQ(*FileName, "File2");
+  FileName = DA.getFileNameForBuildID("333");
+  ASSERT_EQ(*FileName, "File3");
 }