Fix build breakage on FreeBSD after rL289878/rL289881

[dim]

Summary

After rL289878/rL289881, the build on FreeBSD is broken, because
sanitizer_platform_limits_posix.cc attempts to include <utmp.h> and use
struct utmp, neither of which are supported anymore on FreeBSD.

Fix this by adding && !SANITIZER_FREEBSD in two places.

[eugenis]

LGTM
If there is no getutent, you probably want to disable the interceptor in sanitizer_platform_interceptors.h.
Add an ifdef around the declaration of struct_utmp_sz as well.

[dim]

Updated to cover some more cases:

• Don't declare struct_utmp_sz on macOS and FreeBSD
• Don't intercept utmp functions on FreeBSD either

[ed]

I'm the author of FreeBSD's utmpx. LGTM!

lib/sanitizer_common/sanitizer_platform_limits_posix.cc

 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/times.h>
 #include <sys/types.h>
 #include <sys/utsname.h>
 #include <termios.h>
 #include <time.h>
 #include <wchar.h>
-#if !SANITIZER_MAC
+#if !SANITIZER_MAC && !SANITIZER_FREEBSD
 #include <utmp.h>
 #endif
 
 #if !SANITIZER_IOS
 #include <net/route.h>
 #endif
 
 #if !SANITIZER_ANDROID
#if (SANITIZER_LINUX || SANITIZER_FREEBSD) && !SANITIZER_ANDROID
   unsigned struct_shminfo_sz = sizeof(struct shminfo);
   unsigned struct_shm_info_sz = sizeof(struct shm_info);
   int shmctl_ipc_stat = (int)IPC_STAT;
   int shmctl_ipc_info = (int)IPC_INFO;
   int shmctl_shm_info = (int)SHM_INFO;
   int shmctl_shm_stat = (int)SHM_STAT;
 #endif
 
-#if !SANITIZER_MAC
+#if !SANITIZER_MAC && !SANITIZER_FREEBSD
   unsigned struct_utmp_sz = sizeof(struct utmp);
 #endif
 #if !SANITIZER_ANDROID
   unsigned struct_utmpx_sz = sizeof(struct utmpx);
 #endif
 
   int map_fixed = MAP_FIXED;