message: Add error message to matinfo.
diff: @@ -1003,6 +1003,10 @@ static void analyzeSpirv(const std::vector<uint32_t>& spirv, const char* disasse
  }
  }
  }
  + if (currentLineNumber == -1) {
  + cerr << "No #line directives found, did you use a debug version of matc?" << endl;
  + return;
  + }
  }
  // Finally, dump out the annotated GLSL.
  