[lld-macho] Downgrade version mismatch to warning

[int3]

Summary

It's a warning in ld64. While having LLD be stricter would be nice, it
makes it harder for it to be a drop-in replacement into existing builds.

[thakis]

:/

Looks like this lacks test coverage if it needs no test update to go along with it?

[int3]

We did have a test actually. I just I forgot we had %no_fatal_warnings_lld, which makes it not-too-ugly to test for warnings instead of errors... updating that test now

[int3]

update test

lld/MachO/InputFiles.cpp

interleave(
         },
         "/");
     error(toString(input) + " has platform " + platformNames +
           Twine(", which is different from target platform ") +
           getPlatformName(config->platform()));
     return false;
   }
 
-  if (it->minimum <= config->platformInfo.minimum)
-    return true;
-
-  error(toString(input) + " has version " + it->minimum.getAsString() +
+  if (it->minimum > config->platformInfo.minimum)
+    warn(toString(input) + " has version " + it->minimum.getAsString() +
          ", which is newer than target minimum of " +
          config->platformInfo.minimum.getAsString());
-  return false;
+
+  return true;
 }
 
 // Open a given file path and return it as a memory-mapped file.
 Optional<MemoryBufferRef> macho::readFile(StringRef path) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr = MemoryBuffer::getFile(path);
   if (std::error_code ec = mbOrErr.getError()) {
     error("cannot open " + path + ": " + ec.message());
     return None;