Auto merge of #49758 - bjorn3:miri_public_write_discriminant_value, r=oli-obk
Auto merge of #49758 - bjorn3:miri_public_write_discriminant_value, r=oli-obk

miri: Make write_discriminant_value public

aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust