[omniORB] omniORB_2.7.1 changes for AIX 4.3 + xlc 3.6.4.0

[Mark D. Landry]

Here's what I did to get omniORB_2.7.1 working under AIX 4.3 + xlC 3.6.4.0.
Many thanks to Gary Duzan for pointers in the right direction.

In mk/platforms/powerpc_aix_4.2.mk, change:
OMNITHREAD_POSIX_CPPFLAGS = -DNoNanoSleep -DPthreadDraftVersion=8
to:
OMNITHREAD_POSIX_CPPFLAGS = -DPthreadDraftVersion=10

Do NOT add  "-DPthreadSupportThreadPriority". omnithread/posix.cc needs to be
reworked before this can be
used on AIX. Specifically, pthread_setschedparam() is unsupported in 4.3.

In all the 'sharedlib/dir.mk' files under src, change the command
'makeC++SharedLib_r' to 'makeC++SharedLib' and move all options (e.g, -p 40)
_before_ the *.o files (i.e., $(filter-out $(LibSuffixPattern),$^) must be
last.)

Here's an example from src/lib/omnithread/sharedlib/dir.mk:
...
       /usr/lpp/xlC/bin/makeC++SharedLib \
             -lpthreads -p 40 \
             -o $(soname) $(IMPORT_LIBRARY_FLAGS) \
         $(filter-out $(LibSuffixPattern),$^) ; \
...

(It's not clear to me if '-lpthreads' is required in the above statement.)