PR cannot be created in corev-qemu github

[liweiwei90]

We cannot create PR for support of xpulp extensions in corev-qemu github (may be limited in its setting).
The support for xpulp extensions can be found in https://github.com/plctlab/plct-qemu/tree/plct-corev-qemu-upstream.
Xpulp extensions can be enabled by adding parameter "-cpu rv32,xcvalu=true,xcvbi=true,xcvbitmanip=true,xcvhwlp=true,xcvmac=true,xcvmem=true,xcvsimd=true" to qemu-riscv32 or qemu-system-riscv32, such as we can run riscv32 application by

qemu-riscv32  -cpu rv32,xcvalu=true,xcvbi=true,xcvbitmanip=true,xcvhwlp=true,xcvmac=true,xcvmem=true,xcvsimd=true  
<path-to-app>

[liweiwei90]

PR for xpulp extension have been created.