Modifications to force compilation for 32-bit x86-based targets

nanvix being a 32-bit x86-based OS, added relevant flags to force compilation & linking for appropriate targets.
Removing ansi flag may not be a good idead. To quote GCC manual:

"A new edition of the ISO C standard was published in 1999 as ISO/IEC 9899:1999, and is commonly known as C99. GCC has incomplete support for this standard version"

However I'll fix this later - actually, the only part of the code that is not standard is the ata() library.