Add swap32/swap64 definitions for older gcc versions
Add swap32/swap64 definitions for older gcc versions

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