gcc: build with -fstack-usage

will generate an extra file that specifies the maximum amount
of stack used, on a per-function basis.

Using a static stack checker the data can be analysed, for example:
   http://dlbeer.co.nz/oss/avstack.html



Change-Id: I23bd8ce7c4516bd0c7ffb74504e6d379677f25f8
Signed-off-by: Anas Nashif <anas.nashif@intel.com>