[RISCV][compiler-rt] Small fixes for __riscv_feature_bits (#100158)

Changes included:

- Adding CONSTRUCTOR_ATTRIBUTE so that the static data is setup early on
in process lifetime. This is required by gcc docs for
__builtin_cpu_supports which we hope to implement in terms of this.
- Move the length initialization outside of the #if defined(linux) block
so that the length field always reflects the size of the structures even
if non of the feature bits are non-zero.
- Change the __riscv_vendor_feature_bits.length field to match the
length of the actual structure.

Note: Copy from https://github.com/llvm/llvm-project/pull/99958

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Co-authored-by: Philip Reames <preames@rivosinc.com>

0 files changed, 0 insertions, 0 deletions