libobs: Raise out of memory exception manually when out of memory

The previous attempt to clarify an out of memory exception/crash
resulted in the compiler optimizing os_breakpoint() and os_oom() into
the same result, which meant that crash stacks in the wild were still
not specific enough to be helpful. Forcefully differentiating the
functions in Release configuration by having os_breakpoint() only call
__debugbreak() and having os_oom() call RaiseException() should give us
clearer crash stacks.

Amends 94a736f1795c21afd0baa10c0692543b70c17dc5.