Dear all,

array bounds checking was missing a few cases of array sections
that are handled via gfc_conv_expr_descriptor.  Bounds checking
was done for the dimensions with ranges, but not for elemental
dimensions.

The attached patch implements that and fixes pr30802 and also
pr97039, maybe a few more similar cases.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald