XQuartz: Make sure that darwin_all_modifier_mask_additions is 0-terminated

Found by ASan

X.Org X Server 1.17.99.901 Build Date: 20151018
================================================================
==40471==ERROR: AddressSanitizer: global-buffer-overflow on address 0x000101fed7a4 at pc 0x000101584030 bp 0x70000029f920 sp 0x70000029f918
READ of size 4 at 0x000101fed7a4 thread T7
    #0 0x10158402f in DarwinEQInit darwinEvents.c:377
    #1 0x10157f3bc in InitInput darwin.c:566
    #2 0x101be87ad in dix_main main.c:268
    #3 0x10159131b in server_thread quartzStartup.c:66
    #4 0x7fff8a535c12 in _pthread_body (/usr/lib/system/libsystem_pthread.dylib+0x3c12)
    #5 0x7fff8a535b8f in _pthread_start (/usr/lib/system/libsystem_pthread.dylib+0x3b8f)
    #6 0x7fff8a533374 in thread_start (/usr/lib/system/libsystem_pthread.dylib+0x1374)

0x000101fed7a4 is located 0 bytes to the right of global variable 'darwin_all_modifier_mask_additions' defined in 'darwinEvents.c:181:12'
(0x101fed7a0) of size 4
SUMMARY: AddressSanitizer: global-buffer-overflow darwinEvents.c:377 DarwinEQInit
Shadow bytes around the buggy address:
  0x1000203fdaa0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000203fdab0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000203fdac0: f9 f9 f9 f9 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9
  0x1000203fdad0: 00 00 00 00 00 00 00 00 f9 f9 f9 f9 00 00 00 00
  0x1000203fdae0: 00 00 f9 f9 f9 f9 f9 f9 00 00 00 00 00 f9 f9 f9
=>0x1000203fdaf0: f9 f9 f9 f9[04]f9 f9 f9 f9 f9 f9 f9 00 00 00 00
  0x1000203fdb00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000203fdb10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000203fdb20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000203fdb30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000203fdb40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
Thread T7 created by T0 here:
    #0 0x10242ee99 in wrap_pthread_create
(/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/7.0.0/lib/darwin/libclang_rt.asan_osx_dynamic.dylib+0x37e99)
    #1 0x101591089 in create_thread quartzStartup.c:78
    #2 0x101590ed9 in QuartzInitServer quartzStartup.c:95
    #3 0x1015697eb in X11ApplicationMain X11Application.m:1277
    #4 0x101575dc0 in X11ControllerMain X11Controller.m:984
    #5 0x10159171a in server_main quartzStartup.c:127
    #6 0x101540fc0 in do_start_x11_server bundle-main.c:436
    #7 0x101544869 in _Xstart_x11_server mach_startupServer.c:189
    #8 0x101545c96 in mach_startup_server mach_startupServer.c:398
    #9 0x7fff8d1b70f3 in mach_msg_server (/usr/lib/system/libsystem_kernel.dylib+0x110f3)
    #10 0x1015416e7 in main bundle-main.c:774
    #11 0x7fff8bd975ac in start (/usr/lib/system/libdyld.dylib+0x35ac)
    #12 0x0  (<unknown module>)

Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>

hw/xquartz/darwinEvents.c

@@ -178,7 +178,7 @@ static int darwin_x11_modifier_mask_list[] = {
     0
 };
 
-static int darwin_all_modifier_mask_additions[] = { NX_SECONDARYFNMASK, };
+static int darwin_all_modifier_mask_additions[] = { NX_SECONDARYFNMASK, 0 };
 
 static void
 DarwinUpdateModifiers(int pressed,                    // KeyPress or KeyRelease