Change -lgcov with --coverage

`-lgcov` is not supported on macOS.

Closes #5138.

PiperOrigin-RevId: 195081921
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppActionConfigs.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppActionConfigs.java
index 97182b1..0339e13 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppActionConfigs.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppActionConfigs.java
@@ -591,7 +591,6 @@
                     "    flag_group {",
                     "      iterate_over: 'runtime_library_search_directories'",
                     "      flag_group {",
-
                     ifTrue(
                         supportsEmbeddedRuntimes,
                         "    expand_if_all_available: 'is_cc_test_link_action'",
@@ -936,7 +935,7 @@
                     "    action: 'c++-link-nodeps-dynamic-library'",
                     "    action: 'c++-link-executable'",
                     "    flag_group {",
-                    "      flag: '-lgcov'",
+                    "      flag: '--coverage'",
                     "    }",
                     "  }",
                     "  requires {",
diff --git a/tools/cpp/crosstool_lib.bzl b/tools/cpp/crosstool_lib.bzl
index a2dfde6..875386d 100644
--- a/tools/cpp/crosstool_lib.bzl
+++ b/tools/cpp/crosstool_lib.bzl
@@ -259,7 +259,7 @@
     link_flags = flags("-fprofile-instr-generate")
   else:
     compile_flags = flags("-fprofile-arcs", "-ftest-coverage")
-    link_flags = flags("-lgcov")
+    link_flags = flags("--coverage")
   return feature(
     "coverage",
     [