Add /system_ext/etc to config search path

/product should be at the highest search order.
Load libnfc-nci.conf from /system or /system_ext partition if it is not
found in /product or other partitions.

Bug: 157704723
Test: adb push libnfc-nci.conf to /system_ext and check if it is loaded
Change-Id: Ic6a9399497d20ba0bff468d043ce3b5e04453aa8
Merged-In: Ic6a9399497d20ba0bff468d043ce3b5e04453aa8
(cherry picked from commit 707ff2b12514e3bd712066ddaa4b3982ba9c1abc)

src/adaptation/nfc_config.cc

diff --git a/src/adaptation/nfc_config.cc b/src/adaptation/nfc_config.cc
index f406847..264968e 100644
--- a/src/adaptation/nfc_config.cc
+++ b/src/adaptation/nfc_config.cc
@@ -29,9 +29,10 @@
 
 namespace {
 std::string searchConfigPath(std::string file_name) {
-  const vector<string> search_path = {"/odm/etc/", "/vendor/etc/",
-                                      "/product/etc/", "/etc/"};
-  for (string path : search_path) {
+  const std::vector<std::string> search_path = {
+      "/product/etc/", "/odm/etc/", "/vendor/etc/", "/system_ext/etc/", "/etc/",
+  };
+  for (std::string path : search_path) {
     path.append(file_name);
     struct stat file_stat;
     if (stat(path.c_str(), &file_stat) != 0) continue;