[compiler-rt] Follow up fix for the refactoring in https://reviews.llvm.org/D74137.

[Dor1s]

Summary

The refactoring has caused a failure in
http://lab.llvm.org:8011/builders/clang-ppc64le-linux/builds/29265

The idea of failing the symbolization when the symbolizer bufer is too small
was incorrect. The symbolizer can be invoked for other frames that may fit into
the buffer and get symbolized.

[Dor1s]

Self-approval for a quick fix (reverting two lines in https://reviews.llvm.org/D74137).

compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cpp

if (!success || just_read == 0) {
       Report("WARNING: Can't read from symbolizer at fd %d\n", input_fd_);
       return false;
     }
     read_len += just_read;
     if (ReachedEndOfOutput(buffer, read_len))
       break;
     if (read_len + 1 == max_length) {
       Report("WARNING: Symbolizer buffer too small\n");
-      buffer[0] = '\0';
-      return false;
+      read_len = 0;
+      break;
     }
   }
   buffer[read_len] = '\0';
   return true;
 }
 
 bool SymbolizerProcess::WriteToSymbolizer(const char *buffer, uptr length) {
   if (length == 0)