make possible to turn off at compile time online debugging, logging
and external sync functionality

Defines TARGET_DEBUG_DISABLE, TARGET_LOGGING_DISABLE, TARGET_EXT_SYNC_DISABLE
allow to use generated PLC code in low-cost microcontrollers,
integrate into external programs and so on.

main.c:
extern void __run(void);
int main(void)
{
for(;;) {
__run();
// sleep common_ticktime__ ns
// add common_ticktime__ ns to __CURRENT_TIME
}
return 0;
}

Compile for example for arm bare-metal:
../build$ arm-none-eabi-gcc \
-DTARGET_DEBUG_DISABLE -DTARGET_LOGGER_DISABLE
-DTARGET_EXT_SYNC_DISABLE \
-flto -ffunction-sections -fdata-sections -I../../../../matiec/lib/C \
*.c \
-nodefaultlibs --specs=nano.specs -Wl,--static -Wl,--gc-section -Wl,--start-group -lc -lm -lnosys -lgcc -Wl,--end-group

/* Beremiz' header file for use by extensions */

#include "iec_types.h"

#define LOG_LEVELS 4
#define LOG_CRITICAL 0
#define LOG_WARNING 1
#define LOG_INFO 2
#define LOG_DEBUG 3

extern unsigned long long common_ticktime__;
int LogMessage(uint8_t level, char* buf, uint32_t size);
long AtomicCompareExchange(long* atomicvar,long compared, long exchange);