btrace(8) retrieves the types of the arguments of each tracepoint

btrace(8) retrieves the types of the arguments of each tracepoint
from the kernel.  Add them to a cache when needed, and print them
with btrace -l.  If the argument is of type int, print the value
as %d signed integer.  This gives pretty output for refcnt changes.
All other types still use %ul.
The probe and argument number can be used as array index.  Remove
the qsort and search for probe number to simplify the code.  Use
array index for both probes and argument types.
OK mpi@