new should lower to a template function call

[Tim]

On Thursday, 23 July 2020 at 00:47:21 UTC, Andrei Alexandrescu 
wrote:
> One problem I noticed with the current instrumentation of 
> allocations is that it is extremely slow.

Programs compiled with -profile=gc are much faster with this 
change: https://github.com/dlang/druntime/pull/3164

The problem was, that GC.stats was called for every allocation, 
but GC.stats does more than necessary for -profile=gc.

Unfortunately this change breaks the ABI of druntime.