libc/net: static analysis - fix unsafe function
libc/net: static analysis - fix unsafe function

This patch prevents unsafe function.

Change-Id: I05846629de6e7e695b2d1494ef7a77bf4630b2f6
Signed-off-by: Byoungtae Cho <d399e7ab5fdc23c09a148b7028e772c5bd5c24c5@samsung.com>

JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT