Fix the ltp Makefile to allow for installation of all non-c (scripts) files

Fix the ltp Makefile to allow for installation of all non-c (scripts) files

Current the Makefile only builds the .c files and installs
them in the $INSTALL path. However, the ltp directory contains a shell script,
which doen't get copied over (installed) when a "make install"is invoked.

This behaviour causes test 080 to fail since it requires rwtest.sh to be
present in the ltp/ directory.

Tested: Updated the Makefile and ran a static build script & test
080.

Signed-off-by: Akshay Lal <akshaylal@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>