[lib] Add support for Sun libc printstack to zlog_backtrace_sigsafe

[lib] Add support for Sun libc printstack to zlog_backtrace_sigsafe

2006-05-28 Paul Jakma <paul.jakma@sun.com>

	* configure.ac:
	  Check for Sun libc printstack(), add a general HAVE_STACK_TRACE
	  define for lib/log.c, if any supported stack symbol dumping
	  function is found (glibc backtrace/sun libc printstack).
	* log.c: (general) Add support for Sun libc printstack().
	  (hex_append) make the cpp conditional on general HAVE_STACK_TRACE
	  define.
	  (zlog_backtrace_sigsafe) Ditto. Add printstack() version of the
	  the DUMP macro in this function.