mem_perf: NULL-check malloc
mem_perf: Use config to avoid hardcoding clock speed
mem_perf: General cleanup
Add missing include guards
Update Stellaris Launchpad Defconfig
New tests framework

Based on the framework used for commands in the shell, tests are
defined with a macro, then all are run on boot.
Change command section to general user section

This section is not used by the OS, and is reserved for the user
programs to use.
Add strncpy
Tests take two arguements, error message buffer and buffer len

An enum for pass and fail has also been added.
Remove testing tests, add task creation test
Fix memcpy

memcpy was only copying the first byte of each word due to the casting
on the void pointers.
Begin adding tests for string.h library functions
Reorder lib/string.c to put all str functions together
Add strndup
Add more string tests
Move string/number conversion functions to stdlib.h

This is the C standard location for them.
Add strncmp test, fix edge case

In the case where the (n+1)th character did not match, strncmp would
return not a match, even though the first n characters matched.  This is
because when breaking out of the while loop, the pointers had already
been updated to the next letter, but there was no check to return a match
if n == 0.
Add remaining string tests