Android test VMs lack locales

Trying to test a possible fix for QTBUG-63518, I run into the discovery that our Android test VMs don't seem to have any locales installed. Specifically, calls to setlocale(LC_ALL, "en_US") fail, and similar for no_NO, de_DE, sv_SE and (least importantly) the last two with a .ISO8859-1 suffix. This severely limits testing of localization.

Example build exhibiting this; search for tst_QString::localeAwareCompare.

It should be possible to install the locales package on any Linux system and configure it to enable at least en_US.UTF-8 plus, preferably, as many of the locales listed above as possible, plus ar_SA (Arabic, Saudi Arabia). Various tests are skipped if these locales aren't installed; it would be better to do fuller testing.