Bug#831009: ezquake: FTBFS on arm*: cannot convert va_list to pointer

[Aaron M. Ucko]

Source: ezquake
Version: 2.2+git20150324-1
Severity: important
Justification: fails to build from source

Builds of ezquake for arm64, armel, and armhf all failed:

  pr2_cmds.c: In function 'sv_syscall':
  pr2_cmds.c:3007:2: error: cannot convert to a pointer type
    pr2_API[arg] ( 0, (unsigned int) ~0, (pr2val_t*)ap, &ret);
    ^
  Makefile:385: recipe for target '.ezquake/pr2_cmds.o' failed
  make[1]: *** [.ezquake/pr2_cmds.o] Error 1

Please treat va_list as opaque and fix the pr2_API methods to accept
it as such rather than making assumptions about its form.

Thanks!