Replace _exit(-1) with _exit(EXIT_FAILURE).

-1 is not a valid exit status.

Also replace a few exit(1) with exit(EXIT_FAILURE).

Test: mmma bootable/recovery
Change-Id: I4596c8328b770bf95acccc06a4401bd5cabd4bfd
diff --git a/install.cpp b/install.cpp
index 91e4875..ce89e0d 100644
--- a/install.cpp
+++ b/install.cpp
@@ -387,7 +387,7 @@
     // the child process to hang. This deadlock results from an improperly
     // copied mutex in the ui functions.
     fprintf(stdout, "E:Can't run %s (%s)\n", chr_args[0], strerror(errno));
-    _exit(-1);
+    _exit(EXIT_FAILURE);
   }
   close(pipefd[1]);