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/adb_install.cpp b/adb_install.cpp
index fab72f8..79b8df9 100644
--- a/adb_install.cpp
+++ b/adb_install.cpp
@@ -78,7 +78,7 @@
     pid_t child;
     if ((child = fork()) == 0) {
         execl("/sbin/recovery", "recovery", "--adbd", NULL);
-        _exit(-1);
+        _exit(EXIT_FAILURE);
     }
 
     // FUSE_SIDELOAD_HOST_PATHNAME will start to exist once the host