ldbl-128ibm-compat: Add wide character, fortified printing functions

Similarly to what was done for the regular character, fortified printing
functions, this patch combines the mode masks PRINTF_LDBL_USES_FLOAT128
and PRINTF_FORTIFY to provide wide character versions of fortified
printf functions.  It also adds two flavors of test cases: one that
explicitly calls the fortified functions, and another that reuses the
non-fortified test, but defining _FORTIFY_SOURCE as 2.  The first
guarantees that the implementations are actually being tested
(independently of what's in bits/wchar2.h), whereas the second
guarantees that the redirections calls the correct function in the IBM
and IEEE long double cases.

Tested for powerpc64le.

Reviewed-By: Paul E. Murphy <murphyp@linux.ibm.com>