Fix only searching for static libs in zlib, protobuf, etc

[Timchenkovich]

fix #876

[fdr400]

It is bad solution, IMHO, because it contradicts the USE_STATIC_LIBS idea, we won't accept that.

But, to make this more flexible, you can do something like this:

if(NOT DEFINED OPENSSL_USE_STATIC_LIBS)
    set(OPENSSL_USE_STATIC_LIBS ON)
endif()
if(NOT DEFINED Protobuf_USE_STATIC_LIBS)
    set(Protobuf_USE_STATIC_LIBS ON)
endif()