patch 8.2.4480: suspending with CTRL-Z does not work on Android

Problem:    Suspending with CTRL-Z does not work on Android.
Solution:   Do not handle SIGTSTP. (closes #9854)

src/os_unix.c

@@ -887,8 +887,10 @@ sig_tstp SIGDEFARG(sigarg)
     else
 	got_tstp = TRUE;
 
-    // this is not required on all systems, but it doesn't hurt anybody
+#ifndef __ANDROID__
+    // this is not required on all systems
     signal(SIGTSTP, (RETSIGTYPE (*)())sig_tstp);
+#endif
     SIGRETURN;
 }
 #endif