[LyX/master] Cmake preparation to support python3

[Kornel Benko]

commit dbc4c71ef5cefe695955f7b43925d2a12016c28b
Author: Kornel Benko <kor...@lyx.org>
Date:   Tue Mar 10 17:29:58 2015 +0100

    Cmake preparation to support python3

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3f49158..785e37e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -608,8 +608,24 @@ foreach(_spell "ASPELL" "Enchant" "Hunspell")
   endif()
 endforeach()
 
+find_package(PythonInterp 2.7 QUIET)
+if(PYTHONINTERP_FOUND)
+  if(PYTHON_VERSION_STRING VERSION_GREATER 2.8)
+    unset(PYTHONINTERP_FOUND)
+  endif()
+endif()
+
+if (NOT PYTHONINTERP_FOUND)
+  unset(PYTHON_EXECUTABLE CACHE)
+  unset(PYTHON_VERSION_MAJOR)
+  unset(PYTHON_VERSION_MINOR)
+  unset(PYTHON_VERSION_STRING)
+  find_package(PythonInterp 3.3 REQUIRED)
+endif()
+
+set(LYX_PYTHON_EXECUTABLE ${PYTHON_EXECUTABLE} CACHE FILEPATH "Python to be 
used by LyX")
+
 if(LYX_NLS)
-       FIND_PROGRAM(LYX_PYTHON_EXECUTABLE python2 python HINTS 
${GNUWIN32_DIR}/python)
        find_package(LyXGettext)
        if(LYX_PYTHON_EXECUTABLE AND GETTEXT_FOUND)
                add_subdirectory(po "${TOP_BINARY_DIR}/po")