Add std::filesystem support.

Test: ./run_tests.py --bitness 32
Test: ./run_tests.py --bitness 64
Test: ./run_tests.py --bitness 64 --host
Bug: None
Change-Id: Ie277f503b754321eba04b906fa4ee6d670b2c1b2

utils/libcxx/android/test/format.py

@@ -29,8 +29,10 @@ class HostTestFormat(libcxx.test.format.LibcxxTestFormat):
             os.path.join(outdir, 'lib'),
             os.path.join(outdir, 'lib64'),
         ])
-        default_env = {'LD_LIBRARY_PATH': libpath}
-        self.exec_env = default_env if exec_env is None else exec_env
+        env = {'LD_LIBRARY_PATH': libpath}
+        if exec_env is not None:
+            env.update(exec_env)
+        self.exec_env = env
 
 
 class TestFormat(HostTestFormat):