[libc++] Make libc++ and libc++abi's definitions of operator new be exact copies

This allows mechanically copying any changes made to `operator new`
from libc++ into libc++abi as-is. This is also a step towards
de-duplicating this code entirely.

Differential Revision: https://reviews.llvm.org/D153035

GitOrigin-RevId: d53cf0fdd1047534e309fb7a27bd25a962be1c83
1 file changed