When building under W=1, the lack of lkdtm.h in lkdtm_usercopy.c and
lkdtm_rodata.c was discovered. This fixes the issue and consolidates
the common header and the pr_fmt macro for simplicity and regularity
across each test source file.
Signed-off-by: NKees Cook <keescook@chromium.org>

This splits all the remaining tests from lkdtm_core.c into the new
lkdtm_bugs.c file to help separate things better for readability.
Signed-off-by: NKees Cook <keescook@chromium.org>