poly1305/asm/poly1305-x86_64.pl: make it work with linux-x32.

(Imported from upstream's 2460c7f13389d766dd65fa4e14b69b6fbe3e4e3b.)

This is a no-op for us, but avoid a diff with upstream.

Change-Id: I6e875704a38dcd9339371393a4dd523647aeef44
Reviewed-on: https://boringssl-review.googlesource.com/7491
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

crypto/poly1305/asm/poly1305-x86_64.pl

@@ -148,10 +148,16 @@ $code.=<<___;
 	and	8($inp),%rcx
 	mov	%rax,24($ctx)
 	mov	%rcx,32($ctx)
-
+___
+$code.=<<___	if ($flavour !~ /elf32/);
 	mov	%r10,0(%rdx)
 	mov	%r11,8(%rdx)
-
+___
+$code.=<<___	if ($flavour =~ /elf32/);
+	mov	%r10d,0(%rdx)
+	mov	%r11d,4(%rdx)
+___
+$code.=<<___;
 	mov	\$1,%eax
 .Lno_key:
 	ret