ixgbe/base: disable some gcc warnings
ixgbe/base: disable some gcc warnings

This patch disables compilation complain from lower GCC version (less than 4.6).

Note: Only supported versions of GCC are 4.x.

Signed-off-by: Changchun Ouyang <593bf1f161e79772915ea885e47cf0e95f4498c0@intel.com>

tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,venkynv/dpdk-mirror,msune/dpdk,venkynv/dpdk-mirror,mixja/dpdk,msune/dpdk,mixja/dpdk,msune/dpdk,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,john-mcnamara-intel/dpdk,msune/dpdk,tsphillips/dpdk-fork,mixja/dpdk,tsphillips/dpdk-fork,tsphillips/dpdk-fork,mixja/dpdk,john-mcnamara-intel/dpdk