Log message:
Added buildlink3.mk

Log message:
Since py-gflags was added to pkgsrc I though it would be good to have 
glags as well. So this is an import to pkgsrc-wip.

The gflags package contains a library that implements commandline flags
processing. As such it's a replacement for getopt(). Is has increased
flexibility, including built-in support for C++ types like string, and
the ability to define flags in the source file in which they're used.