Don’t use yyerror for each($scalar) experiment err

Don’t use yyerror for each($scalar) experiment err

This is a follow-up to 69e7f50e50.  69e7f50e50 resulted in yyerror
being called twice for the same error, resulting in double diagnos-
tics for where the error occurred:

$ ./perl -e 'keys $scalar, $1'
Experimental keys on scalar is now forbidden at -e line 1, near "$scalar,"
Type of arg 1 to keys must be hash or array (not scalar dereference) at -e line 1, near "$scalar,"
Execution of -e aborted due to compilation errors.

We don’t need ‘near "$scalar,"’ twice.

For the first one we should queue the error directly, using qerror()
(which yyerror itself normally calls), so we don’t get double
diagnostics.