It is of course possible to change this permission but inadvisable.
The basic principle here is that root is NOT to be used as a regular user. You only login as root to perform security sensitive operations such as system upgrades. Therefore anything you must do as root should not in general be viewable by other users.
On that bases root's working area ...
Please note that the installed glibc is an incomplete C runtime.
In order to complete the C runtime you may need to copy in
additional headers that match the compiler you are using since the use
of --sysroot will restrict their lookup to the sysroot.
It is very possible to have multiple versions of glibc on the same system (we do that every day).