bin: use _fullpath in place of realpath on Windows
bin: use _fullpath in place of realpath on Windows

Windows does not support realpath(3); so added ifdefs to switch to
_fullpath on VC++.

Signed-off-by: Fujimoto Seiji <ef879192bb1e41d519c82cf76440dc8e9a530806@clear-code.com>

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