[ARM,MVE] Fix user-namespace violation in arm_mve.h.

Authored by simon_tatham on Mar 12 2020, 2:57 AM.


[ARM,MVE] Fix user-namespace violation in arm_mve.h.

We were generating the declarations of polymorphic intrinsics using
__attribute__((overloadable)). But overloadable is a valid
identifier for an end user to define as a macro in a C program, and if
they do that before including <arm_mve.h>, then we shouldn't cause a
compile error.

Fixed to spell the attribute name __overloadable__ instead.

Reviewers: miyuki, MarkMurrayARM, ostannard

Reviewed By: miyuki

Subscribers: kristof.beyls, dmgreen, danielkiss, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D75997