[Ada] Fix expansion of aggregate for discriminated limited extension

[Pierre-Marie de Rodat]

The presence of the discriminants prevents the values associated with the
components of the parent type from being put into the sub-aggregate built
for the _Parent component.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* exp_aggr.adb (Expand_Record_Aggregate.Build_Back_End_Aggregate):
	Skip the discriminants at the start of the component list before
	looking for the components inherited from the parent in the case
	of a tagged extension.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: patch.diff
Type: text/x-diff
Size: 1135 bytes
Desc: not available
URL: <https://gcc.gnu.org/pipermail/gcc-patches/attachments/20220530/156d5de5/attachment.bin>