Configure: recognize div3w modules and add -DBN_DIV3W.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7589)

Configure

@@ -1354,6 +1354,7 @@ unless ($disabled{asm}) {
     push @{$config{lib_defines}}, "OPENSSL_BN_ASM_MONT" if ($target{bn_asm_src} =~ /-mont/);
     push @{$config{lib_defines}}, "OPENSSL_BN_ASM_MONT5" if ($target{bn_asm_src} =~ /-mont5/);
     push @{$config{lib_defines}}, "OPENSSL_BN_ASM_GF2m" if ($target{bn_asm_src} =~ /-gf2m/);
+    push @{$config{lib_defines}}, "BN_DIV3W" if ($target{bn_asm_src} =~ /-div3w/);
 
     if ($target{sha1_asm_src}) {
 	push @{$config{lib_defines}}, "SHA1_ASM"   if ($target{sha1_asm_src} =~ /sx86/ || $target{sha1_asm_src} =~ /sha1/);