Fix warnings on ruby 1.9.3
Fix warnings on ruby 1.9.3

mvz/ffi,tduehr/ffi,MikaelSmith/ffi,mvz/ffi,ferventcoder/ffi,sparkchaser/ffi,ffi/ffi,tduehr/ffi,tduehr/ffi,mvz/ffi,sparkchaser/ffi,MikaelSmith/ffi,ferventcoder/ffi,sparkchaser/ffi,majioa/ffi,tduehr/ffi,majioa/ffi,ffi/ffi,sparkchaser/ffi,yghannam/ffi,ferventcoder/ffi,yghannam/ffi,ffi/ffi,mvz/ffi,yghannam/ffi,majioa/ffi,yghannam/ffi,majioa/ffi,MikaelSmith/ffi,yghannam/ffi,MikaelSmith/ffi,ferventcoder/ffi