libhx509 is not built according to the same export and calling conventions
on Windows as the other libraries. This change declares and applies
HX509_LIB_FUNCTION, HX509_LIB_NORETURN_FUNCTION, HX509_LIB_CALL and
HX509_LIB_VARIABLE to lib/hx509.
As a result of this change the calling convention for exported functions
will be __stdcall instead of __cdecl.
Change-Id: Ibc3f05e8088030ef7d13798f1d9c9b190bc57797
Appease the compiler by resolving some of the reported warnings,
including:
- Control paths that don't return.
- Potentially uninitialized variables.
- Unused local variables.
- Unreachable code.
- Type safety.
- Synchronize declarations with definitions for functions.
