gcc-4.x: fix wrong warning when using the universal zero initializer {0}

gcc-4.x: fix wrong warning when using the universal zero initializer {0}

When I upgrade efivar to 0.21, it fails to compile with error messages:

| linux.c:850:9: error: missing braces around initializer
[-Werror=missing-braces]
|   struct ifreq ifr = { 0, };
|          ^

It is a known issue of gcc. Backport patch from

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53119

to fix wrong warning when using the universal zero initializer {0}.

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>