Better handling for the process info array

We have phones that have more than 256 PIDs running at one time right
now, so don't segmentation fault when that condition happens.

Free all proc info after it ahs been used.

Also if a process goes away before we read its process name, just print
"<unknown>" instead.

Change-Id: Ia3899be61b047852f62bf3cc6f30eb2fcd797a61
diff --git a/procrank/Android.mk b/procrank/Android.mk
index eb48710..be7c599 100644
--- a/procrank/Android.mk
+++ b/procrank/Android.mk
@@ -19,6 +19,8 @@
 
 LOCAL_C_INCLUDES := $(call include-path-for, libpagemap)
 
+LOCAL_CFLAGS := -Wall -Wextra -Wformat=2 -Werror
+
 LOCAL_SHARED_LIBRARIES := libpagemap
 
 LOCAL_MODULE := procrank