This allows the use of PKCS#11 URI for certificates and keys without
setting the corresponding type as "ENG" and the engine as "pkcs11"
explicitly. If a PKCS#11 URI is provided for certificate, key,
proxy_certificate or proxy_key, the corresponding type is set as "ENG"
if not provided and the engine is set to "pkcs11" if not provided.
Acked-by: Nikos Mavrogiannopoulos
Closes#2333
memdebug.h already contains all required definitions and including
curl_memory.h causes errors like the following:
tests/unit/unit1394.c:119: undefined reference to `Curl_cfree'
tests/unit/unit1394.c:120: undefined reference to `Curl_cfree'
