openssl: remove all uses of USE_SSLEAY

SSLeay was the name of the library that was subsequently turned into
OpenSSL many moons ago (1999). curl does not work with the old SSLeay
library since years. This is now reflected by only using USE_OPENSSL in
code that depends on OpenSSL.

lib/config-symbian.h

@@ -808,10 +808,4 @@
 #define HAVE_ZLIB_H 1
 #endif
 
-/* Enable appropriate definitions only when OpenSSL support is enabled */
-#ifdef USE_SSLEAY
-/* if OpenSSL is in use */
-#define USE_OPENSSL
-#endif
-
 #endif /* HEADER_CURL_CONFIG_SYMBIAN_H */