Fixed C++03 conformance
Fixed C++03 conformance

INT32_MIN and INT64_MIN are not conforming to ISO C++03. This unnecessarily forced C++11 flags to be used, e.g. for G++.
SuperSodaSea/itoa-benchmark,SuperSodaSea/itoa-benchmark,miloyip/itoa-benchmark,miloyip/itoa-benchmark,SuperSodaSea/itoa-benchmark,SuperSodaSea/itoa-benchmark,miloyip/itoa-benchmark,SuperSodaSea/itoa-benchmark,miloyip/itoa-benchmark,miloyip/itoa-benchmark