Use PYTHON_PKGNAMEPREFIX in DOCSDIR and EXAMPLESDIR

[mva]

Summary

Use PYTHON_PKGNAMEPREFIX in DOCSDIR and EXAMPLESDIR to avoid the tedious usage of

DOCSDIR= ${PREFIX}/share/doc/${PKGNAMEPREFIX}${PORTNAME}
EXAMPLESDIR= ${PREFIX}/share/examples/${PKGNAMEPREFIX}${PORTNAME}

in numerous Makefiles. This also is needed to avoid excessive usage of

USE_PYTHON= concurrent  # or
USES= uniquefiles:dirs

for the sake of getting examples or documentation installed.

[antoine]

So, ports using python:build will have pyXX-foo for their DOCSDIR? this doesn't look right...

[antoine]

For some ports that run depend on python like devel/glib20, it doesn't make sense either.
People expect to find the docs in a place like share/doc/glib, not share/doc/pyXX-glib

[mva]

Oh my, I completely forgot about the non-Python world, when doing this. Let me think about those cases once more and how to identify the ports. A quick solution that comes to my mind would be something along the lines

.if  ${PKGNAMEPREFIX} == ${PYTHON_PKGNAMEPREFIX}
DOCSDIR= ...
EXAMPLESDIR= ...
.endif

[koobs]

In D934#15986, @mva wrote:

.if  ${PKGNAMEPREFIX} == ${PYTHON_PKGNAMEPREFIX}
DOCSDIR= ...
EXAMPLESDIR= ...
.endif

@mva Can you update the revision with your suggested code above?