CONFIG: increase cmake requirement for build

- building paraview-5.7 and later requires cmake >= 3.10 itself
  but cmake-3.8 appears to work adequately for building dependent
  components

- use VERSION_GREATER_EQUAL instead of GREATER_EQUAL

src/catalyst/CMakeLists-Project.txt

@@ -12,7 +12,7 @@ if (${ParaView_VERSION} LESS 5.6)
     message(WARNING "==== CAUTION: Catalyst without chdir capability ====")
 endif()
 
-if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
     if (TARGET "VTK::ParallelMPI")
         set(FOAM_USING_VTK_MPI TRUE)
     endif()

src/catalyst/CMakeLists.txt

 #------------------------------------------------------------------------------
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.8)
 cmake_policy(SET CMP0002 NEW)   # For cmake >= 3
 cmake_policy(SET CMP0057 NEW)   # For cmake >= 3.10.2
 
@@ -19,7 +19,7 @@ else()
 endif()
 
 # Define pv_api as MAJ.MIN
-if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
     string(REGEX MATCH [0-9]+[.][0-9]+ pv_api ${ParaView_VERSION})
     set(pv_version "${ParaView_VERSION}")
 else()
@@ -27,7 +27,7 @@ else()
     set(pv_version "${PARAVIEW_VERSION_MAJOR}.${PARAVIEW_VERSION_MINOR}.${PARAVIEW_VERSION_PATCH}")
 endif()
 
-if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
     find_package(ParaView REQUIRED
         COMPONENTS PythonCatalyst
         OPTIONAL_COMPONENTS VTK::ParallelMPI)

src/paraview-plugins/blockMeshReader/CMakeLists.txt

-#-----------------------------------------------------------------------------
-cmake_minimum_required(VERSION 2.8)
+#------------------------------------------------------------------------------
+cmake_minimum_required(VERSION 3.8)
 cmake_policy(SET CMP0002 NEW)   # For cmake >= 3
 cmake_policy(SET CMP0057 NEW)   # For cmake >= 3.10.2
 
@@ -19,7 +19,7 @@ find_package(ParaView REQUIRED)
 if (DEFINED ENV{PARAVIEW_API})
     set(pv_api "$ENV{PARAVIEW_API}")
 else()
-    if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+    if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
         string(REGEX MATCH [0-9]+[.][0-9]+ pv_api ${ParaView_VERSION})
         message("The PARAVIEW_API env was unset, "
             "extracted value from version="
@@ -50,7 +50,7 @@ message("OpenFOAM api   = ${foam_api}, libs = ${foamPvLibQualifier}")
 
 include(CMakeLists-OpenFOAM.txt)
 
-if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
   message("================")
   include(CMakeLists-Project57.txt)
 else()

src/paraview-plugins/foamReader/CMakeLists.txt

-#-----------------------------------------------------------------------------
-cmake_minimum_required(VERSION 2.8)
+#------------------------------------------------------------------------------
+cmake_minimum_required(VERSION 3.8)
 cmake_policy(SET CMP0002 NEW)   # For cmake >= 3
 cmake_policy(SET CMP0057 NEW)   # For cmake >= 3.10.2
 
@@ -19,7 +19,7 @@ find_package(ParaView REQUIRED)
 if (DEFINED ENV{PARAVIEW_API})
     set(pv_api "$ENV{PARAVIEW_API}")
 else()
-    if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+    if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
         string(REGEX MATCH [0-9]+[.][0-9]+ pv_api ${ParaView_VERSION})
         message("The PARAVIEW_API env was unset, "
             "extracted value from version="
@@ -48,7 +48,7 @@ message("OpenFOAM api   = ${foam_api}, libs = ${foamPvLibQualifier}")
 
 include(CMakeLists-OpenFOAM.txt)
 
-if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
   message("================")
   include(CMakeLists-Project57.txt)
 else()

src/runTimePostProcessing/CMakeLists-Project.txt

@@ -13,7 +13,7 @@ unset(FOAM_USING_VTK_MPI)
 
 # Test some characteristics
 
-if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
     if (TARGET "VTK::ParallelMPI")
         set(FOAM_USING_VTK_MPI TRUE)
     endif()

src/runTimePostProcessing/CMakeLists.txt

 #------------------------------------------------------------------------------
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.8)
 cmake_policy(SET CMP0002 NEW)   # For cmake >= 3
 cmake_policy(SET CMP0057 NEW)   # For cmake >= 3.10.2
 
@@ -24,7 +24,7 @@ elseif (EXISTS "$ENV{ParaView_DIR}")
     message("Building with Paraview from $ENV{ParaView_DIR}")
 
     find_package(ParaView REQUIRED)
-    if (${ParaView_VERSION} GREATER_EQUAL 5.7)
+    if (${ParaView_VERSION} VERSION_GREATER_EQUAL 5.7)
         find_package(ParaView REQUIRED
             OPTIONAL_COMPONENTS VTK::ParallelMPI)
     endif()