TIME_MAX not set correctly for OpenBSD in qemu-common.h

Looking at the OpenBSD buildbot logs I noticed a warning that appears to be a bug in the code.
OpenBSD has a 32-bit time_t on all archs at the moment (32-bit and 64-bit).

  CC    i386-softmmu/monitor.o
/buildbot-qemu/default_openbsd_current/build/monitor.c: In function 'expire_password':
/buildbot-qemu/default_openbsd_current/build/monitor.c:944: warning: overflow in implicit constant conversion

qemu-common.h has...

#ifndef TIME_MAX
#define TIME_MAX LONG_MAX
#endif

for OpenBSD this should be INT_MAX.