src/Makefile: Added "-m32" flag to CCFLAGS

This flag is used to force the compilation to 32-bit, which is the most used
architecture in the ProInfo project.

Signed-off-by: Erik Alexandre Pucci <eap08@c3sl.ufpr.br>
Signed-off-by: Danilo K. S. Yorinori <danilok@c3sl.ufpr.br>