various spelling fixes

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/952)
diff --git a/ssl/ssl_cert.c b/ssl/ssl_cert.c
index a4bf76e..dc7debb 100644
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -853,7 +853,7 @@
     return 1;
 }
 
-/* Add certificate chain to internal SSL BUF_MEM strcuture */
+/* Add certificate chain to internal SSL BUF_MEM structure */
 int ssl_add_cert_chain(SSL *s, CERT_PKEY *cpk, unsigned long *l)
 {
     BUF_MEM *buf = s->init_buf;