remove ${prefix}/share/examples and install example in the "correct" location

[petrrr]

This ticket is a follow up on ticket #47687 and goes back to a ​discussion in October 2013.

The background is that ${prefix}/share/examples is not mentioned in hier(7) or the FHS. Only porthier(7) introduced it for some reason.

As a consequence this ticket proposed:

• To remove share/examples from porthier(7) man page
• To audit port for the explicit use of share/examples
• I do not propose to modify build systems (but I doubt this location is often (if ever) used to install examples

There is evidence that the following ports install into share/examples (from my personal installation):

• bison
• expat
• glpk
• jbigkit
• krb5
• mpv
• p5.16-error
• py-google-api
• py-poppler-qt4
• py-py2app
• tsocks
• zlib

and I did a quick review of python ports:

• py-celementtree
• py-freebase
• py-google-api
• py-htmltemplate
• py-keyring
• py-lepton
• py-logilab-constraint
• py-pdfrw
• py-poppler-qt4
• py-py2app
• py-pyfsevents
• py-pylibpcap
• py-pyusb
• py-pyxb
• py-rpncalc
• py-simpy