- fix requested LLVM version

--- CMakeLists.txt.orig	2022-04-30 17:48:46 UTC
+++ CMakeLists.txt
@@ -396,7 +396,7 @@ set(WITH_LLVM no
 
 if (WITH_LLVM)
     set(SYMENGINE_LLVM_COMPONENTS asmparser core executionengine instcombine mcjit native nativecodegen scalaropts vectorize support transformutils)
-    find_package(LLVM REQUIRED ${SYMENGINE_LLVM_COMPONENTS})
+    find_package(LLVM ${FREEBSD_LLVM_VERSION} REQUIRED ${SYMENGINE_LLVM_COMPONENTS})
     set(LLVM_MINIMUM_REQUIRED_VERSION "3.8")
     if (LLVM_PACKAGE_VERSION LESS ${LLVM_MINIMUM_REQUIRED_VERSION})
 	    message(FATAL_ERROR "LLVM version found ${LLVM_PACKAGE_VERSION} is too old.