Many thanks for posting your request on the Mellanox Community.
Based on the information provided, I was not able to reproduce the issue on the default kernel of CentOS 7.6, which is 3.10.0-957.el7.x86_64. I was able to compile and install the latest version available through → svn checkout p/scst/svn - Revision 9610: /trunk scst-svn
As for the 4.4 kernel version, it is impossible to test and validate all new kernels released after our official MLNX_OFED GA driver release. We do support all new kernels delivered through the official Linux distribution channels, so I also tested kernel version 3.10.0-957.27.2.el7, and also with this version I did not experience any issue rebuilding SCST with our latest MLNX_OFED driver.
As SCST is a Community driven subsystem, we recommend to reach out to the community, to see if this is related to the latest kernel-lt.