Remove std::stringstream from the RTC_CHECK implementation.

Since the checks build target is included pretty much everywhere it's hard to reuse any of our other string handling tools. Instead I largely copied AppendFormat from StringBuilder.

Bug: webrtc:8982
Change-Id: I7b23d65d5c21a784113f74d9cbbfded5a616cfc4
Reviewed-on: https://webrtc-review.googlesource.com/97423
Commit-Queue: Jonas Olsson <jonasolsson@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24600}