S390: Fix introduction of __wcscpy and weak wcscpy symbols.

The recent commit 81a14439
has introduced __wcscpy, __GI___wcscpy and the weak alias wcscpy.
This patch also introduces those symbols if glibc is build
with CFLAGS="-march=z13" where the ifunc is omitted.

ChangeLog:

	* sysdeps/s390/wcscpy-vx.S: Add strong aliases to
	__wcscpy, __GI___wcscpy and weak alias to wcscpy.