Fix for SSL_get_server_tmp_key is not available for openssl < 1.0.2

[michaelortmann]

Found by: Jobe
Patch by: michaelortmann
Fixes:

One-line summary:
Fix for SSL_get_server_tmp_key is not available for openssl < 1.0.2

Additional description (if needed):

Test cases demonstrating functionality (if applicable):
tested with openssl 1.0.1u and 1.0.2u
like:

LD_LIBRARY_PATH=/home/michael/opt/openssl-1.0.1u ./configure --with-sslinc=/home/michael/opt/openssl-1.0.1u/include --with-ssllib=/home/michael/opt/openssl-1.0.1u/lib
LD_LIBRARY_PATH=/home/michael/opt/openssl-1.0.1u make config
LD_LIBRARY_PATH=/home/michael/opt/openssl-1.0.1u make
LD_LIBRARY_PATH=/home/michael/opt/openssl-1.0.1u make install
LD_LIBRARY_PATH=/home/michael/opt/openssl-1.0.1u ./eggdrop -t BotA.conf
.jump 127.0.0.1 +6697