Merge pull request #10 from Nibbler999/O2

Build -O2 to workaround reported segfaults on gcc 4.9

binding.gyp

@@ -3,6 +3,7 @@
     {
       'target_name': 'bufferutil',
       'include_dirs': ["<!(node -e \"require('nan')\")"],
+      'cflags!': [ '-O3' ],
       'cflags': [ '-O2' ],
       'sources': [ 'src/bufferutil.cc' ]
     }