uncachedev: uncache test tool.

This adds the uncache test tool (bin/uncache.c). The tool
can be used to test Litmus's char device driver for allocating
uncacheable CPU memory. The tool runs various checks and
gathers basic cache vs. main memory statistics.

In the future, uncache could be extended to quantify the
benefits of the L1, L2, and L3 caches, instead of treating
them as a black box.

Note: Uncache works best when compiled with '-O2'.  While '-O2'
has not been added to the Makefile, other code was updated (code
in tests/ and rtspin), to compile with -O2.

DEPENDS UPON LITMUS-RT PATCH 888d097deb6d1fdc0c89a4f9667fd81cf416cfc7.
Make github/staging complatible with -O2.

Minor changes to test case code to enable compilation
with 'gcc -O2' (gcc v4.7.2).