C++ global object initialization order reversed

[earlephilhower]

@mikee47 and @slaff noted in the Sming repo that the core is calling the c++ ctors in reverse order:
SmingHub/Sming#1825 (comment)

Arduino/cores/esp8266/core_esp8266_main.cpp

Lines 199 to 206 in 074a801

	static void do_global_ctors(void) {
	static struct object ob;
	__register_frame_info( __eh_frame, &ob );
	void (**p)(void) = &__init_array_end;
	while (p != &__init_array_start)
	(*--p)();
	}

I believe w/in a single file/TU, they should be called in the order in which they appear. So calling them backwards may break something if there are inter-object dependencies in global objects.

[igrr]

#2074 had a link to MCVE, not sure if it still is an issue with recent GCC.

[mikee47]

I've added the test case from #2074 and yes, it's still reversed. Thank you.

[earlephilhower]

Closing as the reverse order is still required.