um: Add 2 missing libs to fix various build errors

Fix many build errors (at least 18 build error reports) for uml on i386
by adding 2 more library object files. All missing symbols are
either cmpxchg8b_emu or atomic*386.

Here are a few examples of the build errors that are eliminated:

   /usr/bin/ld: core.c:(.text+0xd83): undefined reference to `cmpxchg8b_emu'
   /usr/bin/ld: core.c:(.text+0x2bb2): undefined reference to `atomic64_add_386'
   /usr/bin/ld: core.c:(.text+0x2c5d): undefined reference to `atomic64_xchg_386'
   syscall.c:(.text+0x2f49): undefined reference to `atomic64_set_386'
   /usr/bin/ld: syscall.c:(.text+0x2f54): undefined reference to `atomic64_set_386'
   syscall.c:(.text+0x33a4): undefined reference to `atomic64_inc_386'
   /usr/bin/ld: syscall.c:(.text+0x33ac): undefined reference to `atomic64_inc_386'
   /usr/bin/ld: net/ipv4/inet_timewait_sock.o: in function `inet_twsk_alloc':
   inet_timewait_sock.c:(.text+0x3d1): undefined reference to `atomic64_read_386'
   /usr/bin/ld: inet_timewait_sock.c:(.text+0x3dd): undefined reference to `atomic64_set_386'
   /usr/bin/ld: net/ipv4/inet_connection_sock.o: in function `inet_csk_clone_lock':
   inet_connection_sock.c:(.text+0x1d74): undefined reference to `atomic64_read_386'
   /usr/bin/ld: inet_connection_sock.c:(.text+0x1d80): undefined reference to `atomic64_set_386'
   /usr/bin/ld: net/ipv4/tcp_input.o: in function `inet_reqsk_alloc':
   tcp_input.c:(.text+0xa345): undefined reference to `atomic64_set_386'
   /usr/bin/ld: net/mac80211/wpa.o: in function `ieee80211_crypto_tkip_encrypt':
   wpa.c:(.text+0x739): undefined reference to `atomic64_inc_return_386'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: kbuild-all@lists.01.org
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: linux-um@lists.infradead.org
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/x86/um/Makefile

@@ -21,6 +21,7 @@ obj-y += checksum_32.o syscalls_32.o
 obj-$(CONFIG_ELF_CORE) += elfcore.o
 
 subarch-y = ../lib/string_32.o ../lib/atomic64_32.o ../lib/atomic64_cx8_32.o
+subarch-y += ../lib/cmpxchg8b_emu.o ../lib/atomic64_386_32.o
 subarch-y += ../kernel/sys_ia32.o
 
 else