Specify LLVM version in find_package

This lets CMake handle the version check and makes configuration succeed on systems with multiple LLVM versions installed where LLVM 17 is not the default version.

CMakeLists.txt

@@ -2,7 +2,7 @@ if (NOT DEFINED LLVM_VERSION_MAJOR)
   project(llvm-cbe)
   set (USE_SYSTEM_LLVM 1)
   cmake_minimum_required(VERSION 3.4.3)
-  find_package(LLVM REQUIRED CONFIG)
+  find_package(LLVM 17 REQUIRED CONFIG)
   message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
   message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
   message(STATUS "LLVM_INCLUDE_DIRS: ${LLVM_INCLUDE_DIRS}")
@@ -15,10 +15,6 @@ if (NOT DEFINED LLVM_VERSION_MAJOR)
   set (CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT LLVM_VERSION_MAJOR EQUAL 17)
-  message(FATAL_ERROR "This project only supports LLVM 17. For older versions of LLVM please check https://github.com/JuliaHubOSS/llvm-cbe/tags")
-endif()
-
 add_subdirectory(lib)
 add_subdirectory(tools)