compile: Use -Wall, not -w

compile: Use -Wall, not -w

For a reason unknown to me GDB was using -w instead of -Wall for 'compile code'.
The problem is later patch for 'compile printf' really needs some warnings to
be able to catch for example missing format string parameters:
	(gdb) compile printf "%d\n"
GCC does not seem to be able to cancel -w (there is nothing like -no-w).

Besides that I think even 'compile code' can benefit from -Wall.

That #ifndef change in print_one_macro() is needed otherwise we get
macro-redefinition warnings for the GCC built-in macros (as -w is no
longer in effect).  For example, without the #ifndef/#endif one gets:

	compile -r -- void _gdb_expr(){int i = 5;}^M
	/tmp/gdbobj-xpU1yB/out4.c:4:0: warning: "__FILE__" redefined [-Wbuiltin-macro-redefined]^M
	/tmp/gdbobj-xpU1yB/out4.c:5:0: warning: "__LINE__" redefined^M
	...

It makes more sense to pick the inferior's version of the macros, hence
#ifndef instead of #undef.

That new testsuite XFAIL is there as if one changes the struct definition to be
compliant with cv-qualifiers (to prevent the warnings):
struct struct_type {
-  struct struct_type *selffield;
+  volatile struct struct_type *selffield;
only then GCC/GDB will hit the crash, described in that GDB PR 18202.

gdb/ChangeLog
2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* compile/compile-c-support.c (print_one_macro): Use #ifndef.
	(generate_register_struct): Use __gdb_uintptr for TYPE_CODE_PTR.
	(c_compute_program): Call generate_register_struct after typedefs.
	* compile/compile-loc2c.c (push, pushf_register_address)
	(pushf_register): Cast to GCC_UINTPTR.
	(do_compile_dwarf_expr_to_c): Use unused attribute.  Add space after
	type.  Use GCC_UINTPTR instead of void *.  Remove excessive cast.
	(compile_dwarf_expr_to_c): Use GCC_UINTPTR instead of void *.
	* compile/compile.c (_initialize_compile): Enable warnings for
	COMPILE_ARGS.

gdb/testsuite/ChangeLog
2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.compile/compile-ops.exp: Cast param to void.
	* gdb.compile/compile.exp: Complete type for _gdb_expr.
	(compile code struct_object.selffield = &struct_object): Add xfail.