LU-10973 lnet: infrastructure to build the LUTF

LU-10973 lnet: infrastructure to build the LUTF

Add flags to turn on/off LUTF building.
Modify the gitignore to ignore .i files which are the
swig interface files used to create python callable APIs
from C APIs

m4 files to search and find python and swig installations needed
for building the LUTF.

Test-Parameters: trivial
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: Idbd23dc457c95425edbf88755ae261ff4de6b0c9
Reviewed-on: https://review.whamcloud.com/38084
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>