[AArch64][SVE] Fix dup/dupq intrinsics for C++.

This patch changes the builtin prototype to use 'b' (boolean) instead
of the default integer element type. That fixes the dup/dupq intrinsics
when compiling with C++.

This patch also fixes one of the defines for __ARM_FEATURE_SVE2_BITPERM.

Reviewed By: kmclaughlin

Differential Revision: https://reviews.llvm.org/D100294