Solution: use NULL instead to avoid build failure with older
compilers.

Solution: initialize to -1, since fd is a file descriptor (int).

Solution: initialize class variable in the same order as they are
defined.

Solution: fix it

Solution: The Coverity Static Code Analyzer was used on libzmq code and found
many issues with uninitialized member variables, some redefinition of variables
hidding previous instances of same variable name and a couple of functions
where return values were not checked, even though all other occurrences were
checked (e.g. init_size() return).

Solution: Phase I - make precompiled.hpp be first file included in every source file

Solution: fix these.