csound-gbs uses the AC_FUNC_MALLOC autoconf macro.  This is described
in autoconf.info:

     If the `malloc' function is compatible with the GNU C library
     `malloc' (i.e., `malloc (0)' returns a valid pointer), define
     `HAVE_MALLOC' to 1.  Otherwise define `HAVE_MALLOC' to 0, ask for
     an `AC_LIBOBJ' replacement for `malloc', and define `malloc' to
     `rpl_malloc' so that the native `malloc' is not used in the main
     project.

Since NetBSD's malloc is not compatible with the GNU C library malloc,
the csound build does
#define malloc rpl_malloc

Then the build fails because csound does not provide an rpl_malloc()
function.  The autoconf info page provides an example rpl_realloc()
function.  However I am not sure if this is the right way to go, because
up to this point csound has functioned great with my malloc().

What do you think?  Should we provide rpl_malloc() and rpl_realloc(), or
should the AC_FUNC_MALLOC and AC_FUNC_REALLOC macros be removed from
configure.ac?