[RISCV][compiler-rt] Update __init_riscv_feature_bits prototype (#101472)
This patch add `void* PlatformArgs` parameter to
`__init_riscv_feature_bits`. `PlatformArgs` allows the platform to
provide pre-computed data and access it without extra effort. For
example, Linux could pass the vDSO object to avoid an extra system call.
```
__init_riscv_feature_bits()
->
__init_riscv_feature_bits(void *PlatformArgs)
```