Remove use of deprecated ustat interface in glibc 2.28:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85835

Taken from upstream:

https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=260684

diff --git a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
index 858bb2184505..de18e56d11cf 100644
--- a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
+++ b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
@@ -157,7 +157,6 @@ typedef struct user_fpregs elf_fpregset_t;
 # 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>
@@ -250,7 +249,19 @@ namespace __sanitizer {
 #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
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<div class='path'>path: <a href='/guix/log/?id=db20b04dac681772a93921b466335bab5b81ae06'>root</a>/<a href='/guix/log/etc?id=db20b04dac681772a93921b466335bab5b81ae06'>etc</a>/<a href='/guix/log/etc/gnu-store.mount.in?id=db20b04dac681772a93921b466335bab5b81ae06'>gnu-store.mount.in</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/etc/gnu-store.mount.in?id=db20b04dac681772a93921b466335bab5b81ae06&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-05-16 15:37:41 +0200'>2020-05-16</span></td><td><a href='/guix/commit/etc/gnu-store.mount.in?id=1a1faa78b0498fbb71f1533beb4b65817c1d3f2a'>etc: Add a systemd unit to bind-mount @storedir@ read-only.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>