c-where-wrt-brace-construct: deal with point following a struct's semicolon.

c-where-wrt-brace-construct: deal with point following a struct's semicolon.

More precisely, when point is right after the terminating semicolon of a
construct like "struct foo { .... } bar;", the function must return
'at-function-end.

* lisp/progmodes/cc-cmds.el (c-where-wrt-brace-construct): Surround an
existing test for 'at-function-end with an `or' form, the other arm testing
for being after the semicolon above.