Disable unfolding sharing for interface files with core definitions
Ticket #22807 (closed) pointed out that the RHS sharing was not compatible with
-fignore-interface-pragmas because the flag would remove unfoldings from
identifiers before the extra-decls
field was populated.
For the 9.6 timescale the only solution is to disable this sharing,
which will make interface files bigger but this is acceptable for the
first release of -fwrite-if-simplified-core
.
For 9.8 it would be good to fix this by implementing #20056 due to the large number of other bugs that would fix.
I also improved the error message in tc_iface_binding to avoid the "no match in record selector" error but it should never happen now as the entire sharing logic is disabled.
Also added the currently broken test for #22807 (closed) which could be fixed by !6080
Fixes #22807 (closed)