[LyX/master] Cmake build: Replace use of deprecated module PythonInterp

[Kornel Benko]

commit d17dfe6fb2cb58b4ae4ebe48f4361b924212d008
Author: Kornel Benko <kornel at lyx.org>
Date:   Thu Nov 28 15:09:11 2019 +0100

    Cmake build: Replace use of deprecated module PythonInterp
    
    Use find_package(Pytnon2 ..) and find_package(Python3 ...) instead
    
    Patch from Patrick (pdvisschere at edpnet.be)
---
 CMakeLists.txt |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 779d9e9..52290e8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -792,17 +792,18 @@ unset(LYX_PYTHON_EXECUTABLE CACHE)
 unset(PYTHON_VERSION_MAJOR)
 unset(PYTHON_VERSION_MINOR)
 unset(PYTHON_VERSION_STRING)
-find_package(PythonInterp 3.5 QUIET)
-if(NOT PYTHONINTERP_FOUND)
+find_package(Python3 3.5 QUIET)
+if(NOT Python3_Interpreter_FOUND)
   unset(PYTHON_EXECUTABLE CACHE)
-  find_package(PythonInterp 2.0 REQUIRED)
+  find_package(Python2 2.0 REQUIRED)
   if(NOT PYTHON_VERSION_STRING VERSION_LESS 2.8)
     message(FATAL_ERROR "Python interpreter found, but is not suitable")
   endif()
+  set(LYX_PYTHON_EXECUTABLE ${Python2_EXECUTABLE} CACHE FILEPATH "Python to be used by LyX")
+else()
+  set(LYX_PYTHON_EXECUTABLE ${Python3_EXECUTABLE} CACHE FILEPATH "Python to be used by LyX")
 endif()
 
-set(LYX_PYTHON_EXECUTABLE ${PYTHON_EXECUTABLE} CACHE FILEPATH "Python to be used by LyX")
-
 if(LYX_NLS)
 	find_package(LyXGettext)
 	if(LYX_PYTHON_EXECUTABLE AND GETTEXT_FOUND)