The last release of glibc 1 was 1995 and can be considered outdated.
Also, the current check prevented building with e.g. musl libc.
Every file that includes common/posix/qplatformdefs.h already has
QT_SOCKLEN_T defined to socklen_t, so remove the definition from those
completely.
This is a continuation of 813f468a and a421e409.
Change-Id: Icf2692a8e814286487662e290a8f844872eefe53
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
1c7950081f