--enable-nspr-threads option

Is the --enable-nspr-threads configure option only supported on certain 
platforms?  NSPR 4.8 seems to build ok with this option on FreeBSD 7.2, 
but the build fails when I try it on Mac OS X 10.5.6 (Intel), linux 
2.6.28, and OpenSolaris 5.11.  The errors I get when building on Mac OS 
X 10.5.6 are shown below.  Thanks for any help.

- Jon


.
.
.
gcc -o prlog.o -c      -Wall -fno-common -g -fPIC  -UNDEBUG -DDEBUG_jon 
  -DDEBUG=1 -DXP_UNIX=1 -DDARWIN=1 -DHAVE_BSD_FLOCK=1 -DHAVE_SOCKLEN_T=1 
-DXP_MACOSX=1 -DHAVE_LCHOWN=1 -DHAVE_STRERROR=1  -DFORCE_PR_LOG 
-D_NSPR_BUILD_ -I../../../dist/include/nspr 
-I../../../../nsprpub/pr/include 
-I../../../../nsprpub/pr/include/private 
../../../../nsprpub/pr/src/io/prlog.c
../../../../nsprpub/pr/src/io/prlog.c: In function ‘PR_LogPrint’:
../../../../nsprpub/pr/src/io/prlog.c:489: warning: implicit declaration 
of function ‘_MD_CURRENT_THREAD’
../../../../nsprpub/pr/src/io/prlog.c:489: warning: initialization makes 
pointer from integer without a cast
../../../../nsprpub/pr/src/io/prlog.c:489: warning: implicit declaration 
of function ‘_MD_GET_INTSOFF’
../../../../nsprpub/pr/src/io/prlog.c:489: warning: implicit declaration 
of function ‘_MD_SET_INTSOFF’
../../../../nsprpub/pr/src/io/prlog.c:507: warning: comparison between 
pointer and integer
../../../../nsprpub/pr/src/io/prlog.c:507: warning: implicit declaration 
of function ‘_MD_CURRENT_CPU’
../../../../nsprpub/pr/src/io/prlog.c:507: error: invalid type argument 
of ‘->’
../../../../nsprpub/pr/src/io/prlog.c:507: warning: passing argument 1 
of ‘_PR_IntsOn’ makes pointer from integer without a cast
../../../../nsprpub/pr/src/io/prlog.c:515: warning: initialization makes 
pointer from integer without a cast
../../../../nsprpub/pr/src/io/prlog.c:528: warning: comparison between 
pointer and integer
../../../../nsprpub/pr/src/io/prlog.c:528: error: invalid type argument 
of ‘->’
../../../../nsprpub/pr/src/io/prlog.c:528: warning: passing argument 1 
of ‘_PR_IntsOn’ makes pointer from integer without a cast
../../../../nsprpub/pr/src/io/prlog.c: In function ‘PR_LogFlush’:
../../../../nsprpub/pr/src/io/prlog.c:536: warning: initialization makes 
pointer from integer without a cast
../../../../nsprpub/pr/src/io/prlog.c:541: warning: comparison between 
pointer and integer
../../../../nsprpub/pr/src/io/prlog.c:541: error: invalid type argument 
of ‘->’
../../../../nsprpub/pr/src/io/prlog.c:541: warning: passing argument 1 
of ‘_PR_IntsOn’ makes pointer from integer without a cast
make[3]: *** [prlog.o] Error 1
make[2]: *** [export] Error 2
make[1]: *** [export] Error 2
make: *** [export] Error 2