Created new branch fix_compilation_warnings

fix compilation error about missing braces

IEC_TIMESPEC has two fields tv_sec and tv_nsec.

Compilation error:
./build/POUS.c:600:45: error: missing braces around initializer [-Werror=missing-braces]
static const STEP temp_step = {{0, 0}, 0, {0, 0}};
^
compilation terminated due to -Wfatal-errors.

fix warning about overflow if matiec is running on 64-bit platform,
but the generated C code will cross-compiled for 32-bit platform

For example:
./build/config.c:29:39: error: large integer implicitly truncated to unsigned type [-Werror=overflow]
unsigned long greatest_tick_count__ = 18446744073709551611UL; /*tick*/
^
compilation terminated due to -Wfatal-errors.
cc1: all warnings being treated as errors

fix C compilation warning about function prototype in __SET_EXTERNAL

Example warning:
./POUS.c:1220:3: error: function declaration isn't a prototype [-Werror=strict-prototypes]
__SET_EXTERNAL(data__->,KN_AUT,,__GET_VAR(data__->KEY_AUT.STATE_OUT));
^
compilation terminated due to -Wfatal-errors.
cc1: all warnings being treated as errors