function_hash: make it easier to handle a file with a list of strings

function_hash: make it easier to handle a file with a list of strings

One thing that we often do is store a list of strings and then check if
a macro name is in the list of strings.

This sets up some helper macros so we don't have to manually register the
file from the smatch_data/ directory every time.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>