Increase the size of our thread stack on 64 bit processors.

Increase the size of our thread stack on 64 bit processors.

We were setting the stack size for each thread to 240KB regardless of
architecture, which meant that in some scenarios we actually had less available
stack space on 64 bit processors (pointers use 8 bytes instead of 4).  So now we
calculate the stack size we reserve based on the platform's __WORDSIZE, which
gives us:

     32 bit -> 240KB
     64 bit -> 496KB
    128 bit -> 1008KB (that's right, we're ready for 128 bit processors)

Patch typed by me but written by several members of #asterisk-dev, including
Kevin, Tilghman, and Qwell.

(closes issue #14932)
Reported by: jpiszcz
Patches:
      06052009_issue14932.patch uploaded by seanbright (license 71)
Tested by: seanbright

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@199626 65c4cc65-6c06-0410-ace0-fbb531ad65f3