PR c/16666
	* c-decl.c (start_function): Don't check for DECL_BUILT_IN when
	determining whether to copy parameter types from a previous
	prototype declaration.

testsuite:
	* gcc.dg/dremf-type-compat-1.c, gcc.dg/dremf-type-compat-2.c,
	gcc.dg/dremf-type-compat-3.c, gcc.dg/dremf-type-compat-4.c,
	gcc.dg/old-style-prom-1.c, gcc.dg/old-style-prom-2.c,
	gcc.dg/old-style-prom-3.c: New tests.

From-SVN: r89883