This patch fixes a bug in the construction of predicate functions.  For a
derived type, we must ensure that the parent type is already frozen so that its
predicate function has been constructed already. This is necessary if the
parent is declared in a nested package and its own freeze point has not been
reached when the derived type is frozen by a local object declaration.

2018-06-11  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_ch13.adb (Build_Predicate_Functions): For a derived type, ensure
	that its parent is already frozen so that its predicate function, if
	any, has already been constructed.

gcc/testsuite/

	* gnat.dg/predicate1.adb: New testcase.

From-SVN: r261422