[reSIProcate] Broken build on macs

[Cullen Jennings <fluffy@xxxxxxxxx>]

It seems something has been broken with the many and strange OS detection in
os/compat.hxx when compiling on OS X.

cj.cisco.sipit.net:repro 109% uname -a
Darwin cj.cisco.sipit.net 7.9.0 Darwin Kernel Version 7.9.0: Wed Mar 30
20:11:17 PST 2005; root:xnu/xnu-517.12.7.obj~1/RELEASE_PPC  Power Macintosh
powerpc


cj.cisco.sipit.net:repro 110% make
g++ -D_REENTRANT  -g  -Wall -I../               -I/usr/local/ssl/include
-I/sw/include -I../sip/build/.. -I/usr/kerberos/include/
-I../sip/build/../contrib/ares -DUSE_ARES -DUSE_SSL -DHAVE_POPT_H -c -o
obj.debug.Darwin.Power_Macintosh/Registrar.o Registrar.cxx
In file included from ../repro/Registrar.hxx:5,
                 from Registrar.cxx:5:
../sip/resiprocate/dum/DialogUsageManager.hxx:465: error: `UInt32' was not
   declared in this scope