libz is a stub

It's no longer copied into Mainline modules. Thus removing the check for
it.

Bug: 155456180
Test: m
Change-Id: I7c0a7f95485c840a3b44c8f3541df1d3cc2c9f04
diff --git a/build/apex/art_apex_test.py b/build/apex/art_apex_test.py
index b97ac23..92505b4 100755
--- a/build/apex/art_apex_test.py
+++ b/build/apex/art_apex_test.py
@@ -618,7 +618,6 @@
     # Check internal native library dependencies.
     self._checker.check_native_library('libcrypto')
     self._checker.check_native_library('libexpat')
-    self._checker.check_native_library('libz')
 
     # TODO(b/139046641): Fix proper 2nd arch checks. For now, just ignore these
     # directories.