S390: Remove s390 specific implementation of bcopy.

S390: Remove s390 specific implementation of bcopy.

Nowadays gcc is automatically replacing a call to bcopy
with a call to memmove.  Thus only old binaries will call
the s390 specific bcopy implementation.

The s390 specific implementation is using an own
implementation for memcpy in the forward case and is
relying on memmove in the backward case.

After removing the s390 specific bcopy, the common code
bcopy is used.  It just performs a tail call to memmove.

ChangeLog:
	* sysdeps/s390/s390-32/bcopy.S: Remove.
	* sysdeps/s390/s390-64/bcopy.S: Likewise.