Set MIPS MSA in ELF Auxiliary Vectors

The MIPS MSA feature is currently not set in the ELF auxiliary vector.

That is, querying the AT_HWCAP key of the ELF auxiliary vectors for a MIPS CPU that has the MSA feature should return a value that has the second bit [0] set.

From [0], `HWCAP_MIPS_MSA` is defined to `1 << 1`.

[0]: https://github.com/torvalds/linux/blob/master/arch/mips/include/uapi/asm/hwcap.h