RFC: AIX pthread patch (v2)

[Jeffrey A Law]

  In message < 200009140441.AAA28096@mal-ach.watson.ibm.com >you write:
  > 	Appended is my current proposal for adding pthread multilib
  > support for AIX 4.3 target of GCC.  This patch changes the t-aix43 target
  > by removing the soft-float multilib and replacing it with pthread.  There
  > is not much need for soft-float on AIX and pthread is much more
  > important. 
  > 
  > 	This patch also modifies gcc/configure so that a new file
  > "gthr-aix.h" always is used; it chooses between gthr-posix.h and
  > gthr-single.h depending on the compiler options.  libstdc++ MT_CFLAGS
  > needs to choose whether to define _PTHREAD for libstdc++/stl based on the
  > compiler options as well.
  > 
  > 	Any problems with committing this patch?
It seems reasonable to me.  

jeff