Make all FATAL-related output appear as 'F' log output.

Previously most of the spew belonging to a FATAL would be 'E' because
Runtime::Abort() used LOG(ERROR) to avoid recursion.

Change-Id: If8f62586c302c239e827c5235ed58ee8fe6e8f5e
diff --git a/src/runtime_linux.cc b/src/runtime_linux.cc
index 8fd81cc..d7b32ee 100644
--- a/src/runtime_linux.cc
+++ b/src/runtime_linux.cc
@@ -80,7 +80,7 @@
       text.erase(index, 1);
     }
     std::string log_line(StringPrintf("\t#%02zd ", i) + function_name + text);
-    LogMessage(filename.c_str(), -1, ERROR, -1).stream() << log_line;
+    LogMessage(filename.c_str(), -1, INTERNAL_FATAL, -1).stream() << log_line;
   }
 
   free(symbols);