* gdb.base/Makefile.in: Try compiling callfuncs.c, if that fails try

	* gdb.base/Makefile.in: Try compiling callfuncs.c, if that fails try
	-DNO_PROTOTYPES.
	* gdb.base/callfuncs.c: Control use of prototypes based on
	NO_PROTOTYPES, not __STDC.
	* gdb.base/callfuncs.exp (do_function_calls): xfail one of the
	t_float_values2 tests if prototypes in use.

	* gdb.base/callfuncs.c (t_float_values, t_float_values2,
	t_double_values):  When checking differences against DELTA, check
	that difference is within the range (-DELTA,DELTA), not just
	(-infinity,DELTA).