libraries/opencv: Better location of site-packages directories

Signed-off-by: Christoph Willing <chris.willing@linux.com>

libraries/opencv/opencv.SlackBuild

@@ -27,13 +27,9 @@
 PRGNAM=opencv
 PRGNAM2=opencv_contrib
 VERSION=${VERSION:-4.0.1}
-BUILD=${BUILD:-2}
+BUILD=${BUILD:-3}
 TAG=${TAG:-_SBo}
 
-PY2VERSION=${PY2VERSION:-2.7}
-PY3VERSION=${PY3VERSION:-3.6}
-
-
 if [ -z "$ARCH" ]; then
   case "$( uname -m )" in
     i?86) ARCH=i586 ;;
@@ -100,8 +96,8 @@ cd build
     -DCMAKE_INSTALL_PREFIX=/usr \
     -DBUILD_SHARED_LIBS=ON \
     -DOPENCV_GENERATE_PKGCONFIG=ON \
-    -DPYTHON2_PACKAGES_PATH=/usr/lib${LIBDIRSUFFIX}/python${PY2VERSION}/site-packages \
-    -DPYTHON3_PACKAGES_PATH=/usr/lib${LIBDIRSUFFIX}/python${PY3VERSION}/site-packages \
+    -DPYTHON2_PACKAGES_PATH=$(python2 -c "import site; print(site.getsitepackages()[0])") \
+    -DPYTHON3_PACKAGES_PATH=$(python3 -c "import site; print(site.getsitepackages()[0])") \
     -DENABLE_PRECOMPILED_HEADERS=OFF \
     -DWITH_IPP=OFF \
     -DWITH_QT=ON \