ada: Fix fixed point text-io when subtype has dynamic range

ada: Fix fixed point text-io when subtype has dynamic range

When the fixed point subtype has dynamic range, for example in the
context of a generic procedure Test where Fixed_Type is a type formal:

  procedure Test (Low, High : Fixed_Type) is
    type New_Subtype is new Fixed_Type range Low .. High;
    package New_Io is new Text_IO.Fixed_IO (New_Subtype);

the compiler would complain with:
 non-static universal integer value out of range

Have the check use the Base type for checking what integer type can be
used. If a given integer type can be used for a base type, it can
also be used for any of its subtypes.

gcc/ada/ChangeLog:

	* libgnat/a-tifiio.adb (OK_Get_32): Use 'Base.
	(OK_Put_32, OK_Get_64, OK_Put_64): Likewise.
	* libgnat/a-tifiio__128.adb (OK_Get_32, OK_Put_32, OK_Get_64)
	(OK_Put_64, OK_Get_128, OK_Put_128): Likewise.
	* libgnat/a-wtfiio.adb (OK_Get_32): Likewise.
	(OK_Put_32, OK_Get_64, OK_Put_64): Likewise.
	* libgnat/a-wtfiio__128.adb (OK_Get_32, OK_Put_32, OK_Get_64)
	(OK_Put_64, OK_Get_128, OK_Put_128): Likewise.
	* libgnat/a-ztfiio.adb (OK_Get_32): Likewise.
	(OK_Put_32, OK_Get_64, OK_Put_64): Likewise.
	* libgnat/a-ztfiio__128.adb (OK_Get_32, OK_Put_32, OK_Get_64)
	(OK_Put_64, OK_Get_128, OK_Put_128): Likewise.