Change DR_NUM_SIMD_VECTOR_REGS to reflect the actual architectural number of registers instead of the preserved number of registers as given by MCXT_NUM_SIMD_SLOTS, as it was intended by beb2ded8.
Fix the upper bound of number of simd registers of xmm, ymm, and zmm in x86 reflected by DR_REG_STOP_XMM, DR_REG_STOP_YMM, and DR_REG_STOP_ZMM in 32-bit mode.
Fixes #3906 (closed)