idmap2: move static functions to anonymous namespaces

Move static functions to anonymous namespaces: this is the contemporary
way to express the same thing.

Test: make idmap2_tests
Change-Id: I41ed387455996db1ac515d04eb560d179b5b5169
diff --git a/cmds/idmap2/tests/Idmap2BinaryTests.cpp b/cmds/idmap2/tests/Idmap2BinaryTests.cpp
index 5c4e857..cfe5361 100644
--- a/cmds/idmap2/tests/Idmap2BinaryTests.cpp
+++ b/cmds/idmap2/tests/Idmap2BinaryTests.cpp
@@ -51,8 +51,10 @@
 
 class Idmap2BinaryTests : public Idmap2Tests {};
 
-static void AssertIdmap(const Idmap& idmap, const std::string& target_apk_path,
-                        const std::string& overlay_apk_path) {
+namespace {
+
+void AssertIdmap(const Idmap& idmap, const std::string& target_apk_path,
+                 const std::string& overlay_apk_path) {
   // check that the idmap file looks reasonable (IdmapTests is responsible for
   // more in-depth verification)
   ASSERT_EQ(idmap.GetHeader()->GetMagic(), kIdmapMagic);
@@ -67,6 +69,8 @@
     ASSERT_NO_FATAL_FAILURE(AssertIdmap(idmap_ref, target_apk_path, overlay_apk_path)); \
   } while (0)
 
+}  // namespace
+
 TEST_F(Idmap2BinaryTests, Create) {
   // clang-format off
   auto result = ExecuteBinary({"idmap2",