test not only if header frei0r.h exists, also use an item
[melted] / src / modules / frei0r /
drwxr-xr-x   ..
-rw-r--r-- 563 Makefile
-rwxr-xr-x 329 configure
-rw-r--r-- 9858 factory.c
-rw-r--r-- 1892 filter_frei0r.c
-rw-r--r-- 5091 frei0r_helper.c
-rw-r--r-- 1094 frei0r_helper.h
-rw-r--r-- 3697 transition_frei0r.c