[Sparc] Don't define __sparcv9 and __sparcv9__ when targeting V8+

Currently, clang defines the three macros __sparcv9, __sparcv9__
and __sparc_v9__ when targeting the V8+ baseline, i.e. using the
V9 instruction set on a 32-bit target.

Since neither gcc nor SolarisStudio define __sparcv9 and __sparcv9__
when targeting V8+, some existing code such as the glibc breaks when
defining either of these two macros on a 32-bit target as they are
used to detect a 64-bit target. Update the tests accordingly.

Fixes PR49562.

Reviewed By: jrtc27, MaskRay, hvdijk

Differential Revision: https://reviews.llvm.org/D98574