Difficulty building on MacOSX

[Mike Alexander]

I'm having trouble building the X window version of Gnucash with the 
recent changes to use Boost for data and time on MacOSX 10.10.3 with 
XCode 6.3.1.  I've tried using both clang as provided by XCode and GCC 
4.8 as provided by MacPorts and get similar failures.  In each case 
either the first or second attempt to run guild as part of the make 
fails with the error

*** error for object 0x7fa6a8413178: incorrect checksum for freed 
object - object was probably modified after being freed.

This happens when some guile code (either unittest-support.scm or 
core-utils.scm) tries to load a GnuCash extension which causes the 
timezone tables to be initialized.  I've had at least two different 
stack traces leading up to this failure.  An example of each is in 
<https://www.dropbox.com/sh/wghtw6xnqv4ygc5/AACtTnDB1oKgSnFoD_E6zREAa?dl=0>. 


I'll keep looking for this, but if anyone has any suggestions, I'd like 
to hear them.  Let me know if you want more information.

            Mike