This patch introduces a dynamically resizable, load factor-based hash
table in unit GNAT.Dynamic_HTables.

2018-08-21  Hristian Kirtchev  <kirtchev@adacore.com>

gcc/ada/

	* libgnat/g-dynhta.adb, libgnat/g-dynhta.ads: New package
	Dynamic_HTable.

gcc/testsuite/

	* gnat.dg/dynhash.adb: New testcase.

From-SVN: r263709