fix many compilation warnings about static variables used by non-static functions

[CC] plc_main.c -> plc_main.o
/tmp/be/build/plc_main.c:396:40: warning: ?LogBuff? is static but used in inline function ?copy_from_log? which is not static
memcpy((char*)buf + remaining, LogBuff[level], size - remaining);
^
/tmp/be/build/plc_main.c:395:22: warning: ?LogBuff? is static but used in inline function ?copy_from_log? which is not static
memcpy(buf, &LogBuff[level][buffpos], remaining);
^
...

^
/tmp/be/build/plc_debugger.c:825:20: warning: ?retain_offset? is static but used in inline function ?BufferIterator? which is not static
Retain(retain_offset, size, real_value_p);
^
/tmp/be/build/plc_debugger.c:823:47: warning: ?retain_offset? is static but used in inline function ?BufferIterator? which is not static
unsigned int next_retain_offset = retain_offset + size;
^
^

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

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#include "iec_types.h"

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#define LOG_LEVELS 4

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#define LOG_CRITICAL 0

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#define LOG_WARNING 1

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#define LOG_INFO 2

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#define LOG_DEBUG 3

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extern unsigned long long common_ticktime__;

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int LogMessage(uint8_t level, char* buf, uint32_t size);

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long AtomicCompareExchange(long* atomicvar,long compared, long exchange);

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