Added support of getting coverage on mac

Bug: chromium:844647
Change-Id: Ia358d3a1dfc9a53149d68f811652f38245a0b408
Reviewed-on: https://webrtc-review.googlesource.com/101041
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Artem Titarenko <artit@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24779}

sdk/BUILD.gn

@@ -43,6 +43,10 @@ if (is_ios || is_mac) {
       "-Wstrict-overflow",
       "-Wmissing-field-initializers",
     ]
+
+    if (use_clang_coverage) {
+      configs = [ "//build/config/coverage:default_coverage" ]
+    }
   }
 
   config("used_from_extension") {