[tsan] Define sigaction_t for Android.

lib/tsan/rtl/tsan_interceptors.cc

 # define F_TLOCK 2      /* Test and lock a region for exclusive use.  */
 # define F_TEST  3      /* Test a region for other processes locks.  */
 
 #define errno (*__errno_location())
 
 typedef void (*sighandler_t)(int sig);
 typedef void (*sigactionhandler_t)(int sig, my_siginfo_t *siginfo, void *uctx);
 
+#if SANITIZER_ANDROID
+struct sigaction_t {
+  u32 sa_flags;
+  union {
+    sighandler_t sa_handler;
+    sigactionhandler_t sa_sgiaction;
+  };
+  __sanitizer_sigset_t sa_mask;
+  void (*sa_restorer)();
+};
+#else
 struct sigaction_t {
 #ifdef __mips__
   u32 sa_flags;
 #endif
   union {
     sighandler_t sa_handler;
     sigactionhandler_t sa_sigaction;
   };
 #if SANITIZER_FREEBSD
   int sa_flags;
   __sanitizer_sigset_t sa_mask;
 #elif SANITIZER_MAC
   __sanitizer_sigset_t sa_mask;
   int sa_flags;
 #else
   __sanitizer_sigset_t sa_mask;
 #ifndef __mips__
   int sa_flags;
 #endif
   void (*sa_restorer)();
 #endif
 };
+#endif
 
 const sighandler_t SIG_DFL = (sighandler_t)0;
 const sighandler_t SIG_IGN = (sighandler_t)1;
 const sighandler_t SIG_ERR = (sighandler_t)-1;
 #if SANITIZER_FREEBSD || SANITIZER_MAC
 const int SA_SIGINFO = 0x40;
 const int SIG_SETMASK = 3;
 #elif defined(__mips__)