ion.c: add O_CLOEXEC to /dev/ion open

Test: device boots and no obvious problems.
Change-Id: I0845b79de49b77878adaf6cd14cc506f7586cccb
diff --git a/libion/ion.c b/libion/ion.c
index 2db8845..a7b22b8 100644
--- a/libion/ion.c
+++ b/libion/ion.c
@@ -34,7 +34,7 @@
 
 int ion_open()
 {
-    int fd = open("/dev/ion", O_RDONLY);
+    int fd = open("/dev/ion", O_RDONLY | O_CLOEXEC);
     if (fd < 0)
         ALOGE("open /dev/ion failed!\n");
     return fd;