Change some RTC_DCHECKs to RTC_DCHECK_EQ
Change some RTC_DCHECKs to RTC_DCHECK_EQ

This makes the error messages more informative.

Bug: webrtc:10398
Change-Id: I161aa4bfa53f60d06500d42c883f18add4c58531
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/127200
Reviewed-by: Karl Wiberg <2c708eb0a58047bf403399f50b3da33ffd2dd444@webrtc.org>
Commit-Queue: Ruslan Burakov <5fbdddd55c506d6fd4238893339ccd8128bde2b3@google.com>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#27071}
ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc