CONFIG: accept 'system' for foamConfigurePaths -paraview

bin/tools/foamConfigurePaths

@@ -66,7 +66,7 @@ Components
   -scotch-path DIR    specify 'SCOTCH_ARCH_PATH' (eg, /opt/scotch_6.0.4)
 
 Graphics
-  -paraview VER       specify 'ParaView_VERSION' (eg, 5.4.1)
+  -paraview VER       specify 'ParaView_VERSION' (eg, 5.4.1 or system)
   -paraview-qt VER    specify 'ParaView_QT' (eg, qt-system)
   -paraview-path DIR  specify 'ParaView_DIR' (eg, /opt/ParaView-5.4.1)
   -vtk  VER           specify 'vtk_version' (eg, VTK-7.1.0)
@@ -580,11 +580,11 @@ do
 
     -paraview | -paraviewVersion | --paraviewVersion)
         # Replace ParaView_VERSION=...
-        expected="[5-9][.0-9]*"
+        expected="[5-9][.0-9]*"  # but also accept system
         optionValue=$(getOptionValue "$@")
         _matches "$optionValue" "$expected" || \
+            [ "$optionValue" != "${optionValue%system}" ] || \
             die "'$1' has bad value: '$optionValue'"
-
         replace etc/config.sh/paraview   ParaView_VERSION "$optionValue"
         replace etc/config.csh/paraview  ParaView_VERSION "$optionValue"
         adjusted=true