buffer: hard-deprecate calling Buffer without new
Checklist
-
make -j4 test
(UNIX), orvcbuild test nosign
(Windows) passes -
commit message follows commit guidelines
Affected core subsystem(s)
buffer
Description of change
Light version of #7152.
We want to make Buffer
a class
so that it can be subclassed. However, instantiating a class
requires new
. This hard-deprecates calling Buffer
without new
.