c-decl.c (build_enumerator): Allow values folding to integer constants but not integer constant expressions...

	* c-decl.c (build_enumerator): Allow values folding to integer
	constants but not integer constant expressions with a pedwarn if
	pedantic.

testsuite:
	* gcc.dg/enum-const-1.c, gcc.dg/enum-const-2.c,
	gcc.dg/enum-const-3.c: New tests.
	* gcc.dg/gnu89-const-expr-1.c, gcc.dg/gnu99-const-expr-1.c: Use
	-pedantic-errors.  Update expected diagnostics.

From-SVN: r146789