Fix man3 reference to CRYPTO_secure_used

CLA: trivial
Reviewed-by: NRichard Levitte <levitte@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2238)

doc/man3/OPENSSL_secure_malloc.pod

@@ -6,7 +6,7 @@ CRYPTO_secure_malloc_init, CRYPTO_secure_malloc_initialized,
 CRYPTO_secure_malloc_done, OPENSSL_secure_malloc, CRYPTO_secure_malloc,
 OPENSSL_secure_zalloc, CRYPTO_secure_zalloc, OPENSSL_secure_free,
 CRYPTO_secure_free, OPENSSL_secure_actual_size, OPENSSL_secure_allocated,
-CYRPTO_secure_used - secure heap storage
+CRYPTO_secure_used - secure heap storage
 
 =head1 SYNOPSIS
 
@@ -30,7 +30,7 @@ CYRPTO_secure_used - secure heap storage
  size_t OPENSSL_secure_actual_size(const void *ptr);
  int OPENSSL_secure_allocated(const void *ptr);
 
- size_t CYRPTO_secure_used();
+ size_t CRYPTO_secure_used();
 
 =head1 DESCRIPTION