[Ada] Type inconsistency in floating_point type declarations

[Ada] Type inconsistency in floating_point type declarations

This patch fixes an inconsistency in the typing of the bounds of a
floting point type declaration, when some bound is given by a dtatic
constant of an explicit type, instead of a real literal, Previous to
this patch the bound of the type retained the given type, leading to
spurious errors in Codepeer.

2019-07-22  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_ch3.adb (Convert_Bound): Subsidiary of
	Floating_Point_Type_Declaration, to handle properly range
	specifications with bounds that may include static constants of
	a given type rather than real literals.

From-SVN: r273680