libc: add dummies for umtp(x) handling

[atopia]

Add getutxent(), setutxent() and endutxent() dummy implementations.

[chelmuth]

Please fix all spelling errors of utmp.

[atopia]

Force-pushed commit bdaa6b8 fixes the spelling.

[skalk]

@atopia the changes of the libc most likely lead to the package build errors of coreutils and coreutils-minimal. Please check the mails of the nightly package buillds for most architectures.

[atopia]

Sorry for the late reaction, 2b1c3e7 should fix the build problems.

[nfeske]

Thanks. Merged to staging.