Add mono_class_set_failure_from_loader_error and use it in a few spots.
Move mono_class_create_from_typedef to use MonoError.

	* class.c (mono_class_create_from_typedef): Do error handling using MonoError
	instead of the loader error for this one.
Add a function to convert from a MonoError to a loader error. Use it with callers of mono_class_create_from_typedef.
Do not define HAVE_ARMV6 unconditionally when cross-compiling for ARM.

This is simply an invalid assumption and certainly not a sane default.

Reverts part of 8f7a7a74.
Always define __ARM_EABI__ when compiling for ARM.

We don't actually support any non-AAPCS ABI.