Generalise search for libboost_python on POSIX

[ajoubertza]

The naming of the boost library has changed around version 1.67, so the current approach in setup.py was failing on newer Linux distributions. Instead of hardcoding the suffix for different
distributions, use the ctypes.utils.find_library function and try the various permutations. The find_library function uses ldconfig and a few other tools under the hood, so it should be reliable.

A new environment variable option was added for the case where the search fails. The library name can be specified directly by setting BOOST_LIB.

Fixes: #300 and #310

Also remove the reporting of boost version from runtime info since we don't get the boost version at runtime - displaying "0.0.0" leads to confusion.

For interest, here's a review of the current Python boost library names:

Path: /usr/lib/x86_64-linux-gnu/, except for CentOS in /usr/lib64/

Distribution	Release	Boost version	Files
Ubuntu	14.04 (Trusty)	1.54 & 1.55	libboost_python-py27.a
			libboost_python-py27.so
			libboost_python-py33.so
			libboost_python-py34.so
			libboost_python.so
Ubuntu	16.04 (Xenial)	1.58	libboost_python-py27.so
			libboost_python-py35.so
			libboost_python.so
Ubuntu	18.04 (Bionic)	1.65	libboost_python-py27.so
			libboost_python-py36.so
			libboost_python.so
			libboost_python3-py36.so
			libboost_python3.so
Ubuntu	19.04 (Disco)	1.67	libboost_python.so
			libboost_python27.so
			libboost_python3-py37.so
			libboost_python3.so
			libboost_python37.so
Ubuntu	20.04 (Focal)	1.71 ?	libboost_python37.so
			libboost_python38.so
Debian	8 (Jessie)	1.55	libboost_python-py27.so
			libboost_python-py34.so
			libboost_python.so
Debian	9 (Stretch)	1.62	libboost_python-py27.so
			libboost_python-py35.so
			libboost_python.so
Debian	10 (Buster)	1.67	libboost_python.so
			libboost_python27.so
			libboost_python3-py37.so
			libboost_python3.so
			libboost_python37.so
Debian	11 (Bullseye)	1.67 ?	libboost_python.so
			libboost_python27.so
			libboost_python3-py37.so
			libboost_python3.so
			libboost_python37.so
			libboost_python38.so
Debian	Experimental (Sid)	1.71 ?	libboost_python37.so
			libboost_python38.so
CentOS	6	1.41	libboost_python-mt.so
			libboost_python.so
CentOS	7	1.53	libboost_python3-mt.so
			libboost_python3.so
			libboost_python3-mt.so
			libboost_python3.so
CentOS	8	1.66	libboost_python3.so
Gentoo	2.6	1.72	libboost_python27.so
			libboost_python36.so

[stanislaw55]

Hi! I think this is great addition to installation process! I run tests on CentOS 7

Results of tests:
CentOS 7, Boost 1.48, Python 2.7: FAIL (headers are located in /usr/include/boost148 and are not picked by compiler)
CentOS 7, Boost 1.53, Python 2.7: PASS
CentOS 7, Boost 1.69, Python 2.7: FAIL (headers are located in /usr/include/boost169 and are not picked by compiler)
CentOS 7, Boost 1.48, Python 3.6: Could not test, no library for Python 3
CentOS 7, Boost 1.53, Python 3.6: PASS
CentOS 7, Boost 1.69, Python 3.6: FAIL (headers are located in /usr/include/boost169 and are not picked by compiler)

I think there should be also added variable like BOOST_HEADERS to point to proper headers directory

[ajoubertza]

@stanislaw55 Thanks for testing. So the standard CentOS install works fine, but not custom.

Can you not use the BOOST_ROOT environment variable, and put your whole custom boost installation in to separate folder? In the example below, we would set BOOST_ROOT=/opt/my_boost:

/opt# tree
.
└── my_boost
    ├── include
    └── lib64

If not, the we can add BOOST_HEADERS, but how to combine BOOST_ROOT and BOOST_HEADERS if both are provided?

[ajoubertza]

@stanislaw55 I've added more options now - please have a look and can you test?

[ajoubertza]

@stanislaw55 I tried out the new environment vars, moving my boost header and libraries around. It works correctly for me. Note: For the headers, the C++ extension code uses includes like
#include <boost/python.hpp>, so the boost headers have to be in a directory called boost.

In your example of /usr/include/boost169, there needs to be a boost directory inside, so there would be a file like /usr/include/boost169/boost/python.hpp.

[stanislaw55]

Hi,
I performed tests again and here are the results

Results of tests:
CentOS 7, Boost 1.48, Python 2.7: PASS (BOOST_HEADERS=/usr/include/boost148)
CentOS 7, Boost 1.53, Python 2.7: PASS
CentOS 7, Boost 1.69, Python 2.7: PASS (BOOST_HEADERS=/usr/include/boost169)
CentOS 7, Boost 1.48, Python 3.6: Could not test, no library for Python 3
CentOS 7, Boost 1.53, Python 3.6: PASS
CentOS 7, Boost 1.69, Python 3.6: PASS (BOOST_HEADERS=/usr/include/boost169)

Looks like it now is possible to compile PyTango on CentOS 7 without hassle!

[ajoubertza]

Looks like it now is possible to compile PyTango on CentOS 7 without hassle!

Excellent. Thanks for the thorough tests.