Cmake: Append OpenSSL include directory to search path

At this point I can build libcurl with OpenSSL, OpenLDAP and LibSSH2.
Supported protocols are at least:
HTTP, HTTPS, FTP, SFTP, TFTP, LDAP, LDAPS, POP3, SMTP
(those are the ones we have regression tests for
in our product's testsuite)

CMakeLists.txt

@@ -289,6 +289,7 @@ if(CMAKE_USE_OPENSSL)
     set(USE_OPENSSL ON)
     set(HAVE_LIBCRYPTO ON)
     set(HAVE_LIBSSL ON)
+    include_directories(${OPENSSL_INCLUDE_DIR})
   endif(OPENSSL_FOUND)
 endif(CMAKE_USE_OPENSSL)