[crt] Remove primitive_break on large allocations.

Since 1996, the C runtime has had a debugger break when an allocation
of 100M or more was made. There's no need for this any longer.

Thanks to Alfredo Beaumont for the prodding on this.
[crt] Fix inline declarations to work with clang.

This doesn't actually change the generated code in the places
that I looked at as the compiler was already deciding to inline.
[crt] Use likely/unlikely.