Add support for modifying pthread_sigmask.signals

This patch makes pthread_sigmask.signals writable as a normal property.
Under the hood appropriate calls are made to reflect the new signal
selection.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Make signalfd.signals writable

This patch makes the signalfd.signals property writable. This is just
syntactic sugar for the existing signalgf.update()

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Add clock_{get,set}time() and clock_getres()

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Add the pyglibc._abc module

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Add pretty-printing repr to all structures

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>