The functions (malloc, free, etc.) that used to be provided in
malloc.h are now provided in cstdlib for C++ files and stdlib.h for
C files. Since we require a C99 compliant compiler it makes sense
that malloc.h is no longer needed.
This patch also modifies all the C++ files to use the <c...>
version of the standard C header files (e.g. <cstdlib> vs
<stdlib.h>). Some of the files used the C++ version and others did
not. There are still a few other header changes that could be done,
but this takes care of much of it.
Rather then lock/unlock the work queue ring for every item, save
tons of pthread lock manipulation by allocating to the producer
in batches. Over the long run, this doesn't change the CPU balance
or hold up either thread, but it eliminates almost 3/4 of the
lock/unlock episodes.
The time change is usually a trivial operation, so instead carry
a timestamp on all the work items and let the work thread decide
on its own when to do a SET_TIME operation. This reduces some
pthread overhead and thus gets us some better performance.