installd: Avoid extra std::string copy

The method is_valid_package_name() takes a const std::string
reference, so it's inefficient to pass a std::string::c_str().

Test: TreeHugger
Change-Id: Ic8b33ce8b6c664f960b5c84f688821e9f7eddf03
diff --git a/cmds/installd/InstalldNativeService.cpp b/cmds/installd/InstalldNativeService.cpp
index a51946d..ae4ea78 100644
--- a/cmds/installd/InstalldNativeService.cpp
+++ b/cmds/installd/InstalldNativeService.cpp
@@ -180,7 +180,7 @@
 }
 
 binder::Status checkArgumentPackageName(const std::string& packageName) {
-    if (is_valid_package_name(packageName.c_str())) {
+    if (is_valid_package_name(packageName)) {
         return ok();
     } else {
         return exception(binder::Status::EX_ILLEGAL_ARGUMENT,