CMake: Add missing dependency on zlib from p3express.

panda/src/express/CMakeLists.txt

@@ -127,7 +127,7 @@ composite_sources(p3express P3EXPRESS_SOURCES)
 
 add_library(p3express ${P3EXPRESS_SOURCES} ${P3EXPRESS_HEADERS})
 target_link_libraries(p3express p3pandabase p3dtool p3dtoolconfig
-  ${_TAR_LIBRARY})
+  ${_TAR_LIBRARY} ${_ZLIB_LIBRARY})
 target_interrogate(p3express ALL)
 
 install(TARGETS p3express DESTINATION lib)