Use native meson python module for python install.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>

libgstc/meson.build

@@ -1,2 +1,4 @@
 subdir('c')
-subdir('python')
+if not get_option('enable-python').disabled()
+  subdir('python')
+endif

libgstc/python/meson.build

@@ -1 +1,25 @@
-run_command('pip3', 'install', '.')
+pymod = import('python')
+python = pymod.find_installation(
+  get_option('with-python-version'),
+  required : get_option('enable-python').enabled(),
+  disabler : true
+)
+
+pythonver = python.language_version()
+if pythonver.version_compare('<3.5')
+  error('Python @0@ is not supported anymore, please port your code to python3.5 or newer.'.format(python.language_version()))
+endif
+
+pygstc_src_files = [
+  'pygstc/__init__.py',
+  'pygstc/gstc.py',
+  'pygstc/gstcerror.py',
+  'pygstc/logger.py',
+  'pygstc/tcp.py'
+]
+
+python.install_sources(
+  pygstc_src_files,
+  subdir : 'pygstc',
+  pure : true
+)

meson_options.txt

@@ -4,13 +4,15 @@ option('enable-examples', type : 'feature', value : 'auto', yield : true, descri
 option('enable-gtk-doc', type : 'boolean', value : false, description : 'Use gtk-doc to build documentation')
 option('enable-systemd', type : 'feature', value : 'auto', description : 'Enable systemd gstd.service install')
 option('enable-initd', type : 'feature', value : 'disabled', description : 'Enable init script install')
+option('enable-python', type : 'feature', value : 'auto', description : 'Install the pygstc library')
 
 # String options
 option('with-gstd-runstatedir', type : 'string', value : '${prefix}/var/run/gstd', description : 'Specify the location of the gstd\'s PID file')
 option('with-gstd-logstatedir', type : 'string', value : '${prefix}/var/log/gstd', description : 'Specify the location of gstd\'s log files')
 option('with-gstd-systemddir', type : 'string', value : 'Systemd default systemduserunitdir', description : 'Specify the location of gstd.service file')
 option('with-gstd-initddir', type : 'string', value : '${sysconfdir}/init.d', description : 'Specify the location of gstd init script')
 option('with-statedir-owner', type : 'string', value : 'root', description : 'Specify the owner of gstd\'s run and log dirs created by the initd script')
+option('with-python-version', type : 'string', value : 'python3', description : 'Specify the python version for pygstc installation')
 
 # Common options
 option('package-name', type : 'string', yield : true,