thunderbird-11.0.1 build fails: error: '_Unwind_Backtrace' was not declared in this scope

[Yuri]

I am getting this error while building thunderbird:

/usr/local/bin/python2.7 ../../config/pythonpath.py \
   -I../../other-licenses/ply \
   -I../../xpcom/idl-parser \
   -I../../xpcom/typelib/xpt/tools \
   ../../xpcom/idl-parser/typelib.py --cachedir=../../xpcom/idl-parser 
-I. -I../../dist/idl 
/usr/ports/mail/thunderbird/work/comm-release/mozilla/xpcom/base/nsIMemory.idl 
-d .deps/nsIMemory.xpt.pp -o _xpidlgen/nsIMemory.xpt
nsIProgrammingLanguage.idl
/usr/local/bin/python2.7 ../../config/pythonpath.py \
   -I../../other-licenses/ply \
   -I../../xpcom/idl-parser \
   -I../../xpcom/typelib/xpt/tools \
   ../../xpcom/idl-parser/typelib.py --cachedir=../../xpcom/idl-parser 
-I. -I../../dist/idl 
/usr/ports/mail/thunderbird/work/comm-release/mozilla/xpcom/base/nsIProgrammingLanguage.idl 
-d .deps/nsIProgrammingLanguage.xpt.pp -o 
_xpidlgen/nsIProgrammingLanguage.xpt
/usr/ports/mail/thunderbird/work/comm-release/mozilla/xpcom/base/nsStackWalk.cpp: 
In function 'nsresult NS_StackWalk(void (*)(void*, void*), PRUint32, 
void*)':
/usr/ports/mail/thunderbird/work/comm-release/mozilla/xpcom/base/nsStackWalk.cpp:1637: 
error: '_Unwind_Backtrace' was not declared in this scope