[Ada] Small comment tweaks for 3 predicates on bit-aligned references

[Ada] Small comment tweaks for 3 predicates on bit-aligned references

They fix a few glitches left and right.  No functional changes.

2019-08-12  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* exp_util.ads (Component_May_Be_Bit_Aligned): Small comment
	tweaks.
	(Possible_Bit_Aligned_Component): Likewise.
	(Type_May_Have_Bit_Aligned_Components): Likewise.
	* exp_util.adb (Component_May_Be_Bit_Aligned): Likewise.
	(Possible_Bit_Aligned_Component): Likewise.
	(Type_May_Have_Bit_Aligned_Components): Likewise.

From-SVN: r274304