Merge pull request #3018 from wangkuiyi/fix_memory_deps_on_device_context

Fix memory deps on device context

paddle/memory/CMakeLists.txt

 add_subdirectory(detail)
 
 cc_library(memory SRCS memory.cc)
-cc_library(memcpy SRCS memcpy.cc)
+cc_library(memcpy SRCS memcpy.cc DEPS device_context)
 
 cc_library(paddle_memory
     DEPS
     memory
     memcpy
     meta_data
-    meta_cache memory_block
-    buddy_allocator system_allocator)
+    meta_cache
+    memory_block
+    buddy_allocator
+    system_allocator)
 
 cc_test(memory_test SRCS memory_test.cc DEPS place paddle_memory)