pw_env_setup: Fix order of PATH

With this, entries in CIPD that come later in the environment config
file come earlier in PATH.

Change-Id: Ie0d29928d0ab752a77ecf0502433f38a499986d2
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/110630
Reviewed-by: Chad Norvell <chadnorvell@google.com>
Commit-Queue: Rob Mohr <mohrr@google.com>
diff --git a/pw_env_setup/py/pw_env_setup/cipd_setup/update.py b/pw_env_setup/py/pw_env_setup/cipd_setup/update.py
index ccc9b74..73140a4 100755
--- a/pw_env_setup/py/pw_env_setup/cipd_setup/update.py
+++ b/pw_env_setup/py/pw_env_setup/cipd_setup/update.py
@@ -342,7 +342,7 @@
     # Set environment variables so tools can later find things under, for
     # example, 'share'.
     if env_vars:
-        for package_file in package_files:
+        for package_file in reversed(package_files):
             name = package_file_name(package_file)
             file_install_dir = os.path.join(install_dir, name)
             # Some executables get installed at top-level and some get