Fix incorrect use of scoped enumerations in format strings (#203)

Scoped enums do not get automatically promoted to their underlying type,
so these uses have undefined behavior and Clang recently started warning
about it.

Bug: chromium:1456289
Change-Id: I9cf4e5a68378930a3bf7d8ac7b0a21eaf0d12670
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/309520
Reviewed-by: Rasmus Brandt <[email protected]>
Auto-Submit: Hans Wennborg <[email protected]>
Commit-Queue: Rasmus Brandt <[email protected]>
Cr-Commit-Position: refs/heads/main@{#40321}

Co-authored-by: Hans Wennborg <[email protected]>

Author: jianjunz

api/video_codecs/h264_profile_level_id.cc

@@ -238,7 +238,8 @@ absl::optional<std::string> H264ProfileLevelIdToString(
   }
 
   char str[7];
-  snprintf(str, 7u, "%s%02x", profile_idc_iop_string, profile_level_id.level);
+  snprintf(str, 7u, "%s%02x", profile_idc_iop_string,
+           static_cast<unsigned>(profile_level_id.level));
   return {str};
 }