dumpstate: add kernel memory fragmentation unusable index

Dump /d/extfrag/unusable_index in bugreports.  It shows the
percentage of memory in each zone that is not available for
allocations for each order.

Change-Id: I2af6680cb609887ea7b3d6107d1aa88bd0206b52
diff --git a/cmds/dumpstate/dumpstate.c b/cmds/dumpstate/dumpstate.c
index ef5c2e9..f3fcca0 100644
--- a/cmds/dumpstate/dumpstate.c
+++ b/cmds/dumpstate/dumpstate.c
@@ -85,6 +85,7 @@
     dump_file("ZONEINFO", "/proc/zoneinfo");
     dump_file("PAGETYPEINFO", "/proc/pagetypeinfo");
     dump_file("BUDDYINFO", "/proc/buddyinfo");
+    dump_file("FRAGMENTATION INFO", "/d/extfrag/unusable_index");
 
 
     dump_file("KERNEL WAKELOCKS", "/proc/wakelocks");