Fix LevelDB builds for modern gcc versions
Fix LevelDB builds for modern gcc versions

LevelDB fails to compile with the current compiler flags on a Debian box running gcc 4.7.1 due to an undefined 'ssize_t'. Other users are also seeing this failure: https://github.com/rvagg/node-levelup/issues/224.

The standalone LevelDB project builds with -std=c++0x which fixes the above error.
snowyu/node-nosql-leveldb,ralphtheninja/leveldown,juliangruber/a-native-module,mafintosh/leveldown-prebuilt,jhead/leveldown,juliangruber/a-native-module-without-prebuild,Level/leveldown-mobile,juliangruber/a-native-module,ralphtheninja/leveldown,No9/leveldown,juliangruber/a-native-module-without-prebuild,timkuijsten/leveldown,Level/leveldown,jhead/leveldown,Level/leveldown-mobile,phillipj/leveldown,snowyu/node-nosql-leveldb,jmanero/flat-rocks,juliangruber/a-native-module,mafintosh/leveldown-prebuilt,Level/rocksdb,gastrodia/leveldown,Level/leveldown-mobile,jmanero/flat-rocks,chjj/rocksdown,juliangruber/a-native-module-without-prebuild,snowyu/node-nosql-leveldb,chjj/rocksdown,Level/leveldown-mobile,snowyu/node-nosql-leveldb,ralphtheninja/leveldown,MathieuCassagne/leveldown,juliangruber/a-native-module-without-prebuild,timkuijsten/leveldown,No9/leveldown,Level/rocksdb,timkuijsten/leveldown,Level/rocksdb,juliangruber/a-native-module,gastrodia/leveldown,gastrodia/leveldown,phillipj/leveldown,No9/leveldown,MathieuCassagne/leveldown,Level/leveldown-mobile,juliangruber/a-native-module,jmanero/flat-rocks,jmanero/flat-rocks,Level/leveldown,ralphtheninja/leveldown,jhead/leveldown,juliangruber/a-native-module-without-prebuild,jhead/leveldown,ralphtheninja/leveldown,mafintosh/leveldown-prebuilt,MathieuCassagne/leveldown,MathieuCassagne/leveldown,MathieuCassagne/leveldown,chjj/rocksdown,gastrodia/leveldown,snowyu/node-nosql-leveldb,phillipj/leveldown,mafintosh/leveldown-prebuilt,phillipj/leveldown,mafintosh/leveldown-prebuilt,phillipj/leveldown,chjj/rocksdown,jmanero/flat-rocks,No9/leveldown,No9/leveldown,gastrodia/leveldown,timkuijsten/leveldown,jhead/leveldown,timkuijsten/leveldown,Level/leveldown