Updated the util/m5/Makefile.arm so that m5op_arm.S is used to create
a static library - libm5.a. Allowing users to insert m5
psuedo-instructions into their applications for fine-grained
checkpointing, switching cpus or dumping statistics. e.g.
#include <m5op.h>
void foo(){
...
m5_reset_stats(<delay>,<period>)
m5_work_begin(<workid>,<threadid>);
...
m5_work_end(<workid>,<threadid>);
m5_dump_stats(<delay>,<period>);
}