Put GetSocketPairs() in unnamed namespace

This avoids conflicting definitions of GetSocketPairs() in outer namespace when
multiple such cc files are complied for one binary.

PiperOrigin-RevId: 286243045

test/syscalls/linux/BUILD

@@ -10,6 +10,7 @@ exports_files(
     [
         "socket.cc",
         "socket_ip_loopback_blocking.cc",
+        "socket_ip_tcp_loopback.cc",
         "socket_ipv4_udp_unbound_loopback.cc",
         "tcp_socket.cc",
         "udp_socket.cc",

test/syscalls/linux/socket_ip_loopback_blocking.cc

@@ -23,6 +23,7 @@
 
 namespace gvisor {
 namespace testing {
+namespace {
 
 std::vector<SocketPairKind> GetSocketPairs() {
   return VecCat<SocketPairKind>(
@@ -43,5 +44,6 @@ INSTANTIATE_TEST_SUITE_P(
     BlockingIPSockets, BlockingSocketPairTest,
     ::testing::ValuesIn(IncludeReversals(GetSocketPairs())));
 
+}  // namespace
 }  // namespace testing
 }  // namespace gvisor

test/syscalls/linux/socket_ip_tcp_loopback.cc

@@ -21,6 +21,7 @@
 
 namespace gvisor {
 namespace testing {
+namespace {
 
 std::vector<SocketPairKind> GetSocketPairs() {
   return {
@@ -34,5 +35,6 @@ INSTANTIATE_TEST_SUITE_P(
     AllUnixDomainSockets, AllSocketPairTest,
     ::testing::ValuesIn(IncludeReversals(GetSocketPairs())));
 
+}  // namespace
 }  // namespace testing
 }  // namespace gvisor