Indent DB lines in x86_64 NASM output.

This is purely cosmetic, but makes it consistent with the DW, etc.,
lines in the block above. The SEH unwind code support will emit a mix of
DW and DB directives and this makes them look more consistent.

Bug: 259
Change-Id: Ia16166ab2495aa813d6076d55af5b62511933c28
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/56125
Reviewed-by: Adam Langley <agl@google.com>
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

crypto/perlasm/x86_64-xlate.pl

@@ -909,11 +909,11 @@ my %globals;
 				    map(s/(0b[0-1]+)/oct($1)/eig,@str);
 				    map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm);
 				    while ($#str>15) {
-					$self->{value}.="DB\t"
+					$self->{value}.="\tDB\t"
 						.join(",",@str[0..15])."\n";
 					foreach (0..15) { shift @str; }
 				    }
-				    $self->{value}.="DB\t"
+				    $self->{value}.="\tDB\t"
 						.join(",",@str) if (@str);
 				    last;
 				  };