[Ada] Remove a SPARK rule about implicit Global

[Ada] Remove a SPARK rule about implicit Global

A rule about implicit Global contract for functions whose names overload
an abstract state was never implemented (and no user complained about
this). It is now removed, so references to other rules need to be
renumbered.

2019-07-01  Piotr Trojanek  <trojanek@adacore.com>

gcc/ada/

	* einfo.adb, sem_ch7.adb, sem_prag.adb, sem_util.adb: Update
	references to the SPARK RM after the removal of Rule 7.1.4(5).

From-SVN: r272875