call uselocale() before freelocale() to make sure that g_local_key has a valid locale.

For tests that call uselocale(), the locale is stored in the
g_userlocale_key thread-specific key. If freelocale() is called later,
then g_uselocal_key points to a deleted pointer. CTS eventually calls
vfprintf to print the result, which calls MB_CUR_MAX and MB_CUR_MAX
accesses the deleted locale stored in g_uselocale_key, causing unpredictable
errors.

Fixed the tests by calling uselocale() with the old locale before
calling freelocale.

(cherry-pick of 8a46cf0f.)

Bug: 17299565
Change-Id: I87efa2a9b16999a11d587f68d3aeedcbe6ac8a2c