Identifiers major and minor are often already taken in POSIX systems due
to their presence in <sys/types.h> as part of the makedev library
function.
This causes compilation failures on FreeBSD and Linux systems with glibc
<2.28.
This change renames the identifiers to major_/minor_.
Differential Revision: https://reviews.llvm.org/D156683
896aada3b6