[CMake] Fix Python 3 lookup when building LLVM with tests

[gargaroff]

Summary

Remove the find_package(Python3 ...) call from Tooling/CMakeLists.txt as
it would override the python 3 version determined in llvm/CMakeLists.txt.
This call did not respect the LLVM_MINIMUM_PYTHON_VERSION.

This fixes the check-all target when building LLVM on a system where the
default python version is not the minimum required version for running tests.

[gargaroff]

Although I find it strange that find_package is called again, even though it is already set through llvm/CMakeLists.txt, this patch does not try to refactor this in any way. The sole purpose is to make tests executable again in our downstream setup.

[serge-sans-paille]

Did you try just removing that find_package?

[gargaroff]

In D99715#2663588, @serge-sans-paille wrote:

Did you try just removing that find_package?

Simply removing it also works. I just wasn't sure whether it might be required by something else, but if not I can go ahead and change this diff to remove it instead.

[steveire]

Yes, please remove the line instead.

[gargaroff]

Remove find_package call from Tooling/CMakeLists.txt

[serge-sans-paille]

LGTM, thanks!

clang/lib/Tooling/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   Option
   FrontendOpenMP
   Support
   )
 
 add_subdirectory(Core)
 add_subdirectory(Inclusions)
 add_subdirectory(Refactoring)
 add_subdirectory(ASTDiff)
 add_subdirectory(DumpTool)
 add_subdirectory(Syntax)
 add_subdirectory(DependencyScanning)
 add_subdirectory(Transformer)
 
-find_package(Python3 COMPONENTS Interpreter)
-
 # Replace the last lib component of the current binary directory with include
 string(FIND ${CMAKE_CURRENT_BINARY_DIR} "/lib/" PATH_LIB_START REVERSE)
 if(PATH_LIB_START EQUAL -1)
   message(FATAL_ERROR "Couldn't find lib component in binary directory")
 endif()
 math(EXPR PATH_LIB_END "${PATH_LIB_START}+5")
 string(SUBSTRING ${CMAKE_CURRENT_BINARY_DIR} 0 ${PATH_LIB_START} PATH_HEAD)
 string(SUBSTRING ${CMAKE_CURRENT_BINARY_DIR} ${PATH_LIB_END} -1 PATH_TAIL)