Diagnose use of [*] in old-style parameter definitions (PR c/88704).

Diagnose use of [*] in old-style parameter definitions (PR c/88704).

GCC wrongly accepts [*] in old-style parameter definitions because
because parm_flag is set on the scope used for those definitions and,
unlike the case of a prototype in a function definition, there is no
subsequent check to disallow this invalid usage.  This patch adds such
a check.  (At this point we don't have location information for the
[*], so the diagnostic location isn't ideal.)

Bootstrapped with no regressions for x86_64-pc-linux-gnu.

	PR c/88704
gcc/c:
	* c-decl.c (store_parm_decls_oldstyle): Diagnose use of [*] in
	old-style parameter definitions.

gcc/testsuite:
	* gcc.dg/vla-25.c: New test.

From-SVN: r278917