Increasing visibility of api/transport build targets.

Bug: None
Change-Id: Ib5fd40907f737acc47414064d92aa5b80641faf0
Reviewed-on: https://webrtc-review.googlesource.com/c/111060
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25649}

api/transport/BUILD.gn

@@ -27,6 +27,7 @@ rtc_source_set("enums") {
 }
 
 rtc_static_library("network_control") {
+  visibility = [ "*" ]
   sources = [
     "network_control.h",
     "network_types.cc",
@@ -43,6 +44,7 @@ rtc_static_library("network_control") {
 }
 
 rtc_static_library("goog_cc") {
+  visibility = [ "*" ]
   sources = [
     "goog_cc_factory.cc",
     "goog_cc_factory.h",