eal/windows: fix debug build

eal/windows: fix debug build

When building DPDK on Windows in debug mode the following
warning appear:

warning: token pasting of ',' and __VA_ARGS__ is a GNU extension
[-Wgnu-zero-variadic-macro-arguments] #define open(path, flags, ...)
_open(path, flags, ##__VA_ARGS__)

Modify the 'open' macro to avoid it.

Fixes: 45d62067c237 ("eal: make OS shims internal")
Cc: stable@dpdk.org
Signed-off-by: Tal Shnaiderman <talshn@nvidia.com>
Acked-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>