s390x assembly pack: improve portability.

Some of the instructions used in latest additions are extension
ones. There is no real reason to limit ourselves to specific
processors, so [re-]adhere to base instruction set.

RT#4548
Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/chacha/asm/chacha-s390x.pl

@@ -147,7 +147,8 @@ $code.=<<___;
 .type	ChaCha20_ctr32,\@function
 .align	32
 ChaCha20_ctr32:
-	cl${g}ije	$len,0,.Lno_data	# $len==0?
+	lt${g}r	$len,$len			# $len==0?
+	bzr	%r14
 	a${g}hi	$len,-64
 	l${g}hi	%r1,-$frame
 	stm${g}	%r6,%r15,`6*$SIZE_T`($sp)
@@ -279,7 +280,6 @@ $code.=<<___;
 	stmg	%r0,%r3,$stdframe+4*12($sp)
 
 	lm${g}	%r6,%r15,`$frame+6*$SIZE_T`($sp)
-.Lno_data:
 	br	%r14
 
 .align	16

crypto/s390xcpuid.S

@@ -143,9 +143,9 @@ CRYPTO_memcmp:
 	je	.Lno_data
 
 .Loop_cmp:
-	llc	%r0,0(%r2)
+	llgc	%r0,0(%r2)
 	la	%r2,1(%r2)
-	llc	%r1,0(%r3)
+	llgc	%r1,0(%r3)
 	la	%r3,1(%r3)
 	xr	%r1,%r0
 	or	%r5,%r1