Fix CMake build

PiperOrigin-RevId: 388493683
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1e6c5f1..8b0c350 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4883,8 +4883,8 @@
 ENDIF()
 
 ADD_LIBRARY(all_microkernels OBJECT ${ALL_MICROKERNEL_SRCS} ${TABLE_SRCS})
-ADD_LIBRARY(indirection src/indirection.c
-ADD_LIBRARY(packing src/packing.c))
+ADD_LIBRARY(indirection OBJECT src/indirection.c)
+ADD_LIBRARY(packing OBJECT src/packing.c)
 
 IF(XNNPACK_LIBRARY_TYPE STREQUAL "default")
   ADD_LIBRARY(XNNPACK ${COLD_SRCS} ${HOT_SRCS} ${TABLE_SRCS} ${PROD_MICROKERNEL_SRCS})