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

Bug: 120024673
Test: mmm frameworks/base/cmds/idmap2; check output
Change-Id: I8768169fb7b541eb6b1aa3311c46a710eb71aac9
diff --git a/cmds/idmap2/libidmap2/CommandLineOptions.cpp b/cmds/idmap2/libidmap2/CommandLineOptions.cpp
index 28c3797..cabc8f3 100644
--- a/cmds/idmap2/libidmap2/CommandLineOptions.cpp
+++ b/cmds/idmap2/libidmap2/CommandLineOptions.cpp
@@ -26,13 +26,11 @@
 
 #include "idmap2/CommandLineOptions.h"
 
-namespace android {
-namespace idmap2 {
+namespace android::idmap2 {
 
 std::unique_ptr<std::vector<std::string>> CommandLineOptions::ConvertArgvToVector(
     int argc, const char** argv) {
-  return std::unique_ptr<std::vector<std::string>>(
-      new std::vector<std::string>(argv + 1, argv + argc));
+  return std::make_unique<std::vector<std::string>>(argv + 1, argv + argc);
 }
 
 CommandLineOptions& CommandLineOptions::OptionalFlag(const std::string& name,
@@ -111,8 +109,8 @@
   }
 
   if (!mandatory_opts.empty()) {
-    for (auto iter = mandatory_opts.cbegin(); iter != mandatory_opts.cend(); ++iter) {
-      outError << "error: " << *iter << ": missing mandatory option" << std::endl;
+    for (const auto& opt : mandatory_opts) {
+      outError << "error: " << opt << ": missing mandatory option" << std::endl;
     }
     Usage(outError);
     return false;
@@ -159,5 +157,4 @@
   }
 }
 
-}  // namespace idmap2
-}  // namespace android
+}  // namespace android::idmap2