Fixed LuaJIT native build on Raspberry Pi.

Missed out one more condition check before applying -m32/64 flag.

Source/ThirdParty/LuaJIT/DetectTargetArchitecture.cmake

@@ -93,7 +93,9 @@ if (ARCH_BITS EQUAL 64)
         set (ARCH_BITS 32)
     endif ()
 endif ()
-set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -m${ARCH_BITS}")
+if (TARGET_LJARCH STREQUAL x64)
+    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -m${ARCH_BITS}")
+endif ()
 
 find_string ("LJ_HASJIT (1)" "${TARGET_TESTARCH}" HASJIT ${VARIANT})
 if (HASJIT)