Optimization: Helping gcc with function attributes

[tqh]

I wanted to experiment with gcc's attribute((fastcall)) which makes the functions two first arguments being passed in registers. I added it to kernel functions I thought would be called a lot. The resulting OS seems to be very responsive, although no measurements have been done.

My patch is just for inspiration, it is ugly and I did not really care about compability or if I break any API. Providing it here for those interested. It is used A LOT in Mozilla sources btw although hidden behind macros. It might be useful along with other function attributes in critical parts.

Function attributes are described here: http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html

[tqh]

Ugly fastcall patch

[tqh]

attribute has two underscores in front and after that went missing in the submission.

[tqh]

Ugly fastcall patch against r25229