sanitizer: Use pre-computed size of struct ustat for Linux

[hjl.tools]

Summary

<sys/ustat.h> has been removed from glibc 2.28 by:

commit cf2478d53ad7071e84c724a986b56fe17f4f4ca7
Author: Adhemerval Zanella <[e-mail]>
Date: Sun Mar 18 11:28:59 2018 +0800

Deprecate ustat syscall interface

This patch uses pre-computed size of struct ustat for Linux to fix

https://bugs.llvm.org/show_bug.cgi?id=37418

[kcc]

LGTM, thanks!

[hjl.tools]

Can you check it in for me? Thanks.

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

 #include <sys/kd.h>
 #include <sys/shm.h>
 #include <sys/statvfs.h>
 #include <sys/timex.h>
 #if defined(__mips64)
 # include <sys/procfs.h>
 #endif
 #include <sys/user.h>
-#include <sys/ustat.h>
 #include <linux/cyclades.h>
 #include <linux/if_eql.h>
 #include <linux/if_plip.h>
 #include <linux/lp.h>
 #include <linux/mroute.h>
 #include <linux/mroute6.h>
 #include <linux/scc.h>
 #include <linux/serial.h>

 #if SANITIZER_LINUX || SANITIZER_FREEBSD
   unsigned struct_rlimit_sz = sizeof(struct rlimit);
   unsigned struct_timespec_sz = sizeof(struct timespec);
   unsigned struct_utimbuf_sz = sizeof(struct utimbuf);
   unsigned struct_itimerspec_sz = sizeof(struct itimerspec);
 #endif // SANITIZER_LINUX || SANITIZER_FREEBSD
 
 #if SANITIZER_LINUX && !SANITIZER_ANDROID
-  unsigned struct_ustat_sz = sizeof(struct ustat);
+  // Use pre-computed size of struct ustat to avoid <sys/ustat.h> which
+  // has been removed from glibc 2.28.
+#if defined(__aarch64__) || defined(__s390x__) || defined (__mips64) \
+  || defined(__powerpc64__) || defined(__arch64__) || defined(__sparcv9) \
+  || defined(__x86_64__)
+#define SIZEOF_STRUCT_USTAT 32
+#elif defined(__arm__) || defined(__i386__) || defined(__mips__) \
+  || defined(__powerpc__) || defined(__s390__)
+#define SIZEOF_STRUCT_USTAT 20
+#else
+#error Unknown size of struct ustat
+#endif
+  unsigned struct_ustat_sz = SIZEOF_STRUCT_USTAT;
   unsigned struct_rlimit64_sz = sizeof(struct rlimit64);
   unsigned struct_statvfs64_sz = sizeof(struct statvfs64);
 #endif // SANITIZER_LINUX && !SANITIZER_ANDROID
 
 #if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID
   unsigned struct_timex_sz = sizeof(struct timex);
   unsigned struct_msqid_ds_sz = sizeof(struct msqid_ds);
   unsigned struct_mq_attr_sz = sizeof(struct mq_attr);