Add header that declares memcpy function

It fixes following issue when compiling adb with host libraries:

In file included from core/adb/client/adb_install.cpp:31:
In file included from core/adb/adb.h:30:
In file included from core/adb/socket.h:28:
core/adb/types.h:237:9: error: use of undeclared identifier 'memcpy'; did you mean 'wmemcpy'?
        memcpy(copy->data(), first_block->data() + begin_offset_, copy->size());
        ^~~~~~
        wmemcpy
/usr/include/wchar.h:262:17: note: 'wmemcpy' declared here
extern wchar_t *wmemcpy (wchar_t *__restrict __s1,

Change-Id: I233e533fa7a5e2ed98190e34e32ddbaddc528558