Add CLING_EXPORT macro.

interpreter/cling/lib/Interpreter/CIFactory.cpp

interpreter/cling/test/CodeGeneration/Symbols.C

interpreter/cling/test/Interfaces/address.C

interpreter/cling/test/Interfaces/address_lib.c

interpreter/cling/test/LibraryCall/call.C

interpreter/cling/test/LibraryCall/call_lib.c

interpreter/cling/test/LibraryCall/callable_lib.C

interpreter/cling/test/Pragmas/add_env_path.C

interpreter/cling/test/Pragmas/call_lib.c

interpreter/cling/test/Pragmas/load.C

interpreter/cling/test/lit.cfg