Fix Make, Make clean and when the src directories are cloned

Fix Make, Make clean and when the src directories are cloned

Update the rules for Make clean and distclean.
Update make not to clone the repositories if they are already
cloned, simply pull, checkout the tags and build.
Changes in this patch:
1. QEMU is built just once in .../src directory.
.../src_vanilla and .../src_cuse don't contain qemu anymore
2. 'make clean' deletes all built *.o files
3. 'make distclean' deletes all built and generated files
(distclean is used instead of cleanse now)
4. 'make' calls 'git pull' when repository is cloned already

JIRA: VSPERF-94

Change-Id: I80f9a135580b450fb4606cf947661049ff509548
Signed-off-by: Radek Zetik <radekx.zetik@intel.com>
Reviewed-by: Billy O Mahony <billy.o.mahony@intel.com>
Reviewed-by: Gene Snider <eugene.snider@huawei.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>