Fix crash in "perf stat memory_malloc"

This patch fixes "perf stat memory_malloc". This used to crash: When the
tracepoint was first reached, we called per_cpu_counter::increment();
If this was the first time this function was called, the lazy symbol
resolution caused program::resolve() to be called, which among other things
allocates memory again - yielding endless recursion.

The fix is to call per_cpu_counter::increment() once, on some silly junk
counter, before setting the tracepoint probe. This will ensure that this
function will have already been resolved by the time it is called in an
actual tracepoint.

Fixes #239.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>