kernel: Add stack_info to k_thread

This patck adds the stack information into the k_thread data structure.
The information will be set by when creating a new thread (_new_thread)
and will be used by the scheduling process.

Change-Id: Ibe79fe92a9ef8bce27bf8616d8e0c878508c267d
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@linaro.org>

kernel/Kconfig

diff --git a/kernel/Kconfig b/kernel/Kconfig
index d0c16a6..03e586b 100644
--- a/kernel/Kconfig
+++ b/kernel/Kconfig
@@ -138,6 +138,14 @@
 	This option specifies the size of the stack used by interrupt
 	service routines (ISRs), and during kernel initialization.
 
+config THREAD_STACK_INFO
+	bool
+	prompt "Thread stack info"
+	default n
+	help
+	This option allows each thread to store the thread stack info into
+	the k_thread data structure.
+
 config  THREAD_CUSTOM_DATA
 	bool
 	prompt "Thread custom data"