build: drop extra options -lssl -lcrypto

These options are superfluous, because these dependencies is
already passed to the linker when linking marialdb-connector-c
and library dependencies are transitive by default with
target_link_libraries().

See: mariadb-connector-c/CMakeLists.txt:272 and
https://cmake.org/cmake/help/v3.3/command/target_link_libraries.html#libraries-for-both-a-target-and-its-dependents.

Closes #52

Author: romanhabibov

mysql/CMakeLists.txt

@@ -1,6 +1,6 @@
 add_library(driver SHARED driver.c)
 add_dependencies(driver mariadbclient)
-target_link_libraries(driver mariadbclient -lssl -lcrypto)
+target_link_libraries(driver mariadbclient)
 set_target_properties(driver PROPERTIES PREFIX "" OUTPUT_NAME "driver")
 install(TARGETS driver LIBRARY DESTINATION ${TARANTOOL_INSTALL_LIBDIR}/mysql)
 install(FILES init.lua DESTINATION ${TARANTOOL_INSTALL_LUADIR}/mysql)