Fix python site-packages dir

Fixes the need for PYTHONPATH on Gentoo

Signed-off-by: Alec Ari <neotheuser@ymail.com>

Author: NTULINUX

debian/linuxcnc.install.in

@@ -110,7 +110,7 @@ usr/bin/xyzbc-trt-gui
 
 usr/lib/lib*.so.*
 usr/lib/linuxcnc
-usr/lib/python3
+usr/lib/python3*
 usr/lib/tcltk
 
 usr/share/axis

src/configure.ac

@@ -1657,7 +1657,7 @@ fi
 AC_MSG_RESULT([$PYTHON_TK_VERSION])
 
 AC_MSG_CHECKING(for site-package location)
-SITEPY="$($PYTHON -c 'import sysconfig; s = sysconfig.get_scheme_names(); m=list(set(("deb_system", "rpm_prefix")) & set(s)); print(sysconfig.get_path("platlib", m.__getitem__(0))) if m else print("/usr/lib/python3/dist-packages");')"
+SITEPY="$PYTHON_SITE_PKG"
 AC_MSG_RESULT($SITEPY)
 
 AC_MSG_CHECKING(for working GLU quadrics)