The Linux and *BSD interceptors are almost identical, except for *BSD,
where the overridden intercepted function is not defined weak due to
some incompliant linker behaviour.
Since most of the interception machinery is shared between Linux and
*BSD (see INTERCEPT_FUNCTION macro), it makes sense to unify interceptor
definition and declarations as much as possible to ease future changes.
NFC.
Reviewed By: dvyukov, vitalybuka
Differential Revision: https://reviews.llvm.org/D151318
19b137f0c2