Patch: Use _Unwind_GetIPInfo in stacktrace.cc

[Steve Ellcey]

> Yes, if libstdc++ introduces a configure test, then I'll use it in 
> libjava too. Hopefully it can be put in the common aclocal.m4?
> 
> Bryce

The libstdc++ configure test that I created checks for
__Unwind_GetIPInfo by doing a link test (compiles and links a program,
checks for an undef of __Unwind_GetIPInfo).

In libjava/configure.ac there is the comment:

	[dnl Botheration.  Now we've got to detect the exception model.
	dnl Link tests against libgcc.a are problematic since -- at least
	dnl as of this writing -- we've not been given proper -L bits for
	dnl single-tree newlib and libgloss.

and also:

	   AC_MSG_CHECKING([for global timezone variable])
	   dnl FIXME: we don't want a link check here because that won't work
	   dnl when cross-compiling.  So instead we make an assumption that
	   dnl the header file will mention timezone if it exists.
	   dnl Don't find the win32 function timezone

This makes me wonder if the libstdc++ check would work for libjava.  If
it would I will create a C++ patch and try to get it checked in but if it
won't work for java because java doesn't want to try linking anything
during configuration then how do we check for __Unwind_GetIPInfo?

Steve Ellcey
sje@cup.hp.com