We now only have the executable code section boundaries at hand,
so can only infer offsets for symbols within those boundaries.

Symbols outside of this region are non-text symbols, pointless for
traceback symbolization anyway.

2018-05-22  Olivier Hainque  <hainque@adacore.com>

gcc/ada/

	* libgnat/s-dwalin.adb (Enable_Cache): Skip symbols outside of the
	executable code section boundaries.

From-SVN: r260510