s390x assembly pack: enable clang build

clang imposes some restrictions on the assembler code that
gcc does not.
Signed-off-by: NPatrick Steuer <patrick.steuer@de.ibm.com>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10330)

(cherry picked from commit 6f93f06135cbbd36c3fe98d63717e8303a5d559b)

Conflicts:
	crypto/perlasm/s390x.pm (non-existant)
	crypto/s390xcpuid.pl (code to be changed non-existant)

crypto/bn/asm/s390x-mont.pl

@@ -145,7 +145,7 @@ $code.=<<___;
 	lghi	$NHI,0
 	alcgr	$NHI,$nhi
 
-	la	$j,8(%r0)	# j=1
+	la	$j,8		# j=1
 	lr	$count,$num
 
 .align	16
@@ -197,7 +197,7 @@ $code.=<<___;
 	lghi	$NHI,0
 	alcgr	$NHI,$nhi
 
-	la	$j,8(%r0)	# j=1
+	la	$j,8		# j=1
 	lr	$count,$num
 
 .align	16
@@ -241,7 +241,7 @@ $code.=<<___;
 	la	$ap,$stdframe($sp)
 	ahi	$num,1		# restore $num, incidentally clears "borrow"
 
-	la	$j,0(%r0)
+	la	$j,0
 	lr	$count,$num
 .Lsub:	lg	$alo,0($j,$ap)
 	lg	$nlo,0($j,$np)
@@ -255,7 +255,7 @@ $code.=<<___;
 	lghi	$NHI,-1
 	xgr	$NHI,$AHI
 
-	la	$j,0(%r0)
+	la	$j,0
 	lgr	$count,$num
 .Lcopy:	lg	$ahi,$stdframe($j,$sp)	# conditional copy
 	lg	$alo,0($j,$rp)

crypto/rc4/asm/rc4-s390x.pl

@@ -184,7 +184,7 @@ $code.=<<___;
 RC4_set_key:
 	stm${g}	%r6,%r8,6*$SIZE_T($sp)
 	lhi	$cnt,256
-	la	$idx,0(%r0)
+	la	$idx,0
 	sth	$idx,0($key)
 .align	4
 .L1stloop:
@@ -194,8 +194,8 @@ RC4_set_key:
 
 	lghi	$ikey,-256
 	lr	$cnt,$len
-	la	$iinp,0(%r0)
-	la	$idx,0(%r0)
+	la	$iinp,0
+	la	$idx,0
 .align	16
 .L2ndloop:
 	llgc	$acc,2+256($ikey,$key)
@@ -212,7 +212,7 @@ RC4_set_key:
 	jz	.Ldone
 	brct	$cnt,.L2ndloop
 	lr	$cnt,$len
-	la	$iinp,0(%r0)
+	la	$iinp,0
 	j	.L2ndloop
 .Ldone:
 	lm${g}	%r6,%r8,6*$SIZE_T($sp)