idmap2: fix clang-tidy warnings [modernize-*]

Bug: 120024673
Test: mmm frameworks/base/cmds/idmap2; check output
Change-Id: I8768169fb7b541eb6b1aa3311c46a710eb71aac9
diff --git a/cmds/idmap2/tests/CommandLineOptionsTests.cpp b/cmds/idmap2/tests/CommandLineOptionsTests.cpp
index 243d23a..c27d27a 100644
--- a/cmds/idmap2/tests/CommandLineOptionsTests.cpp
+++ b/cmds/idmap2/tests/CommandLineOptionsTests.cpp
@@ -38,8 +38,7 @@
 
 #include "TestHelpers.h"
 
-namespace android {
-namespace idmap2 {
+namespace android::idmap2 {
 
 TEST(CommandLineOptionsTests, Flag) {
   bool foo = true;
@@ -193,5 +192,4 @@
             std::string::npos);
 }
 
-}  // namespace idmap2
-}  // namespace android
+}  // namespace android::idmap2