RFR: 8000617: It should be possible to allocate memory without the VM dying.

[Keith McGuigan]

Personally, I don't have strong feelings on how this is implemented, 
other than it should be done in a way that's maintainable going forward 
and easily understandable by future generations of hotspot developers. 
With this in mind, the only potential solution that I don't like is 
using a boolean with naked true/false values as discriminators.

Using some sort of "failure mode" parameter is the natural way to do 
this, whether it be enums, std::nothrow_t, or whatever.  Since 
std::nothrow_t already has a type and one value, and is already present 
in the few places we're interested in, it seemed easy to simple just add 
a new value to use.  However if this ends up being confusing because 
this is not the normal use of std::notype_t, then fine, we can do 
something else.

--
- Keith