[LLVM][CMake] Prefer to find libffi.a if present llvm#78779

Premerge land patch from Joseph

Change-Id: I7dd70621ad9d2f96a07cbdc65ff0f6226c2a41fb

Author: ronlieb

llvm/cmake/modules/FindFFI.cmake

@@ -34,7 +34,7 @@ else()
   endif()
 endif()
 
-find_library(FFI_LIBRARIES ffi PATHS ${FFI_LIBRARY_DIR})
+find_library(FFI_LIBRARIES NAMES libffi.a ffi PATHS ${FFI_LIBRARY_DIR})
 
 if(FFI_LIBRARIES)
   include(CMakePushCheckState)