[Ada] Generate ada_target_properties

[Ada] Generate ada_target_properties

Generate target-dependent info into a file named ada_target_properties.
This information is used by tools for static analysis: they need to know
the size of standard types for a given run-time library. This metadata
is meant to be saved at the root of the run-time directory.

2019-08-19  Jerome Guitton  <guitton@adacore.com>

gcc/ada/

	* Makefile.rtl (system.o): New target to add generation of
	target properties.
	* gcc-interface/Makefile.in (install-gnatlib): Install
	ada_target_properties.

From-SVN: r274658