- fix llvm version

--- CMakeLists.txt.orig	2021-08-03 13:32:13 UTC
+++ CMakeLists.txt
@@ -147,7 +147,7 @@ endif()
 # NOTE: do it early so that we can set up
 # compiler flags based on the LLVM version
 # if needed.
-find_package(LLVM REQUIRED CONFIG)
+find_package(LLVM ${FREEBSD_LLVM_VERSION} REQUIRED CONFIG)
 
 if(${LLVM_VERSION_MAJOR} LESS 10)
   message(FATAL_ERROR "LLVM >= 10 is required.")
