Replace all 'sizeof(x)/sizeof(*x)' with lenof.

I noticed a few of these in the course of preparing the previous
commit. I must have been writing that idiom out by hand for _ages_
before it became totally habitual to #define it as 'lenof' in every
codebase I touch. Now I've gone through and replaced all the old
verbosity with nice terse lenofs.

sshblowf.c

@@ -702,7 +702,4 @@ static const ssh2_cipheralg *const blowfish_list[] = {
     &ssh_blowfish_ssh2
 };
 
-const ssh2_ciphers ssh2_blowfish = {
-    sizeof(blowfish_list) / sizeof(*blowfish_list),
-    blowfish_list
-};
+const ssh2_ciphers ssh2_blowfish = { lenof(blowfish_list), blowfish_list };