tree a90e03fe30509e11dbacec3a6ccb437279c58ce8
parent 60acc06b6a32051db6bdf7c48973cafeb30da464
author dmcardle <dmcardle@google.com> 1576260372 -0800
committer Copybara-Service <copybara-worker@google.com> 1576260409 -0800

Remove string libraries from //third_party/quic/platform.

The removed libraries have migrated to //third_party/quiche.

See:
  * //third_party/quiche/common/platform/api:quiche_str_cat_lib
  * //third_party/quiche/common/platform/api:quiche_string_piece_lib
  * //third_party/quiche/common/platform/api:quiche_text_utils_lib

gfe-relnote: n/a, no functional change
PiperOrigin-RevId: 285420767
Change-Id: I274bc31fd12599790f2e8d5fa227a244fd41e158