[LTP] [PATCH] include/lapi: add leaf Makefile

[Jinseok Kim]

Hi,

Thanks for the review!

If we switch to generic_trunk, the current directory is not checked;
only subdirectories are traversed.

For example, running `make check` in include/ will descend into
include/lapi, and running `make check` in include/lapi will descend
into include/lapi/syscalls.

Thanks,
Jinseok.