This commit adds support for reading the `AnonHugePages` field from `/proc/meminfo`.
The values in this field allow monitoring the [THP](https://www.kernel.org/doc/Documentation/vm/transhuge.txt) usage by systems that use this type of memory
This commit replaces `os.Setenv` with `t.Setenv` in tests. The
environment variable is automatically restored to its original value
when the test and all its subtests complete.
Reference: https://pkg.go.dev/testing#T.Setenv
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
