Fix Windows CMake compiler/OS detection.

Replaced deprecated `DetermineVSServicePack`macro with recommended
`CMAKE_CXX_COMPILER_VERSION`.

Deleted custom `OSVersion` detection.  The windows-specific code is
highly outdated, and on other systems simply returns `CMAKE_SYSTEM`.
We will get values like `windows-10.0.17763`, but this is preferable
to `unknownwin`, and saves us needing to maintain a separate cmake file.

cmake/EigenDetermineOSVersion.cmake

@@ -1,46 +0,0 @@
-# The utility function DetermineOSVersion aims at providing an
-# improved version of the CMake variable ${CMAKE_SYSTEM} on Windows
-# machines.
-#
-# Usage:
-#  include(EigenDetermineOSVersion)
-#  DetermineOSVersion(OS_VERSION)
-#  message("OS: ${OS_VERSION}")
-
-# - A little helper variable which should not be directly called
-function(DetermineShortWindowsName WIN_VERSION win_num_version)
-   if    (${win_num_version} VERSION_EQUAL "6.1")
-       set(_version "win7")
-   elseif(${win_num_version} VERSION_EQUAL "6.0")
-       set(_version "winVista")
-   elseif(${win_num_version} VERSION_EQUAL "5.2")
-       set(_version "winXpProf")
-   elseif(${win_num_version} VERSION_EQUAL "5.1")
-       set(_version "winXp")
-   elseif(${win_num_version} VERSION_EQUAL "5.0")
-       set(_version "win2000Prof")
-   else()
-       set(_version "unknownWin")
-   endif()
-   set(${WIN_VERSION} ${_version} PARENT_SCOPE)
-endfunction()
-
-function(DetermineOSVersion OS_VERSION)
-  if (WIN32 AND CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
-    file (TO_NATIVE_PATH "$ENV{COMSPEC}" SHELL)
-    exec_program( ${SHELL} ARGS "/c" "ver" OUTPUT_VARIABLE ver_output)
-				
-      string(REGEX MATCHALL "[0-9]+"
-           ver_list "${ver_output}")
-      list(GET ver_list 0 _major)		   
-      list(GET ver_list 1 _minor)
-				
-    set(win_num_version ${_major}.${_minor})
-    DetermineShortWindowsName(win_version "${win_num_version}")
-    if(win_version)
-      set(${OS_VERSION} ${win_version} PARENT_SCOPE)
-    endif()
-  else()
-    set(${OS_VERSION} ${CMAKE_SYSTEM} PARENT_SCOPE)
-  endif()
-endfunction()

cmake/EigenDetermineVSServicePack.cmake

@@ -1,41 +0,0 @@
-include(CMakeDetermineVSServicePack)
-
-# The code is almost identical to the CMake version. The only difference is that we remove
-# _DetermineVSServicePack_FastCheckVersionWithCompiler which lead to errors on some systems.
-function(EigenDetermineVSServicePack _pack)
-    if(NOT DETERMINED_VS_SERVICE_PACK OR NOT ${_pack})
-        if(NOT DETERMINED_VS_SERVICE_PACK)
-            _DetermineVSServicePack_CheckVersionWithTryCompile(DETERMINED_VS_SERVICE_PACK _cl_version)
-            if(NOT DETERMINED_VS_SERVICE_PACK)
-                _DetermineVSServicePack_CheckVersionWithTryRun(DETERMINED_VS_SERVICE_PACK _cl_version)
-            endif()
-        endif()
-
-        if(DETERMINED_VS_SERVICE_PACK)
-            if(_cl_version)
-                # Call helper function to determine VS version
-                _DetermineVSServicePackFromCompiler(_sp "${_cl_version}")
-              
-                # temporary fix, until CMake catches up
-                if (NOT _sp)
-                    if(${_cl_version} VERSION_EQUAL "17.00.50727.1")
-                        set(_sp "vc110")
-                    elseif(${_cl_version} VERSION_EQUAL "17.00.51106.1")
-                        set(_sp "vc110sp1")
-                    elseif(${_cl_version} VERSION_EQUAL "17.00.60315.1")
-                        set(_sp "vc110sp2")
-                    elseif(${_cl_version} VERSION_EQUAL "17.00.60610.1")
-                        set(_sp "vc110sp3")
-                    else()
-                        set(_sp ${CMAKE_CXX_COMPILER_VERSION})
-                    endif()
-                endif()
-                
-                if(_sp)
-                    set(${_pack} ${_sp} CACHE INTERNAL
-                        "The Visual Studio Release with Service Pack")
-                endif()
-            endif()
-        endif()
-    endif()
-endfunction()

cmake/EigenTesting.cmake

@@ -462,15 +462,7 @@ endmacro()
 
 macro(ei_get_compilerver VAR)
     if(MSVC)
-      # on windows system, we use a modified CMake script
+      set(${VAR} "${CMAKE_CXX_COMPILER_VERSION}")
-      include(EigenDetermineVSServicePack)
-      EigenDetermineVSServicePack( my_service_pack )
-
-      if( my_service_pack )
-        set(${VAR} ${my_service_pack})
-      else()
-        set(${VAR} "na")
-      endif()
     elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "PGI")
       set(${VAR} "${CMAKE_CXX_COMPILER_ID}-${CMAKE_CXX_COMPILER_VERSION}")
     else()
@@ -605,10 +597,7 @@ macro(ei_set_build_string)
   ei_get_compilerver(LOCAL_COMPILER_VERSION)
   ei_get_cxxflags(LOCAL_COMPILER_FLAGS)
 
-  include(EigenDetermineOSVersion)
+  set(TMP_BUILD_STRING ${CMAKE_SYSTEM}-${LOCAL_COMPILER_VERSION})
-  DetermineOSVersion(OS_VERSION)
-
-  set(TMP_BUILD_STRING ${OS_VERSION}-${LOCAL_COMPILER_VERSION})
 
   if (NOT ${LOCAL_COMPILER_FLAGS} STREQUAL  "")
     set(TMP_BUILD_STRING ${TMP_BUILD_STRING}-${LOCAL_COMPILER_FLAGS})