Xm-tests 01_memset_basic_pos.test and 03_memset_random_pos.test start

Xm-tests 01_memset_basic_pos.test and 03_memset_random_pos.test start
domUs with 64MB of memory,
and assume that all of that memory is available in the domU. They then
perform various xm memset tests
based on the assumed starting conditions.

When netback & blkback are comiled into the domU kernel, they eat about
5MB. This mismatch will cause
01_memset_basic_pos.test to fail every time. 03_memset_random_pos.test
will probably fail, but can
pass with some lucky numbers from the random number generator.

This patch changes both tests to read the starting memory allocation from
the balloon driver in the domU.

Signed-off-by: Jim Dykman <dykman@us.ibm.com>