A new kind BTF_KIND_TAG is added to .BTF to encode
btf_tag attributes. The format looks like
CommonType.name : attribute string
CommonType.type : attached to a struct/union/func/var.
CommonType.info : encoding BTF_KIND_TAG
kflag == 1 to indicate the attribute is
for CommonType.type, or kflag == 0
for struct/union member or func argument.
one uint32_t : to encode which member/argument starting from 0.
If one particular type or member/argument has more than one attribute,
multiple BTF_KIND_TAG will be generated.
Differential Revision: https://reviews.llvm.org/D106622
4948927058