IcuRegistration: Avoid string copy

We pass by const reference to avoid a copy.

Test: TreeHugger
Change-Id: Icf3fce985f4b9ae1cccc9031f9a0ff4518b2130f
diff --git a/libandroidicuinit/IcuRegistration.cpp b/libandroidicuinit/IcuRegistration.cpp
index 353ce5c..b60cdde 100644
--- a/libandroidicuinit/IcuRegistration.cpp
+++ b/libandroidicuinit/IcuRegistration.cpp
@@ -211,7 +211,7 @@
   // it.
 }
 
-bool IcuRegistration::pathExists(const std::string path) {
+bool IcuRegistration::pathExists(const std::string& path) {
   struct stat sb;
   return stat(path.c_str(), &sb) == 0;
 }