Compiling hal produces

addon-macbookpro-backlight.c:205: error: dereferencing pointer to incomplete type
addon-macbookpro-backlight.c:208: warning: implicit declaration of function
'pci_cleanup'
addon-macbookpro-backlight.c:208: warning: nested extern declaration of
'pci_cleanup'
addon-macbookpro-backlight.c:165: warning: unused variable 'ret'
addon-macbookpro-backlight.c:164: warning: unused variable 'endptr'
make[5]: *** [addon-macbookpro-backlight.o] Error 1
make[4]: *** [all-recursive] Error 1
make[3]: *** [all-recursive] Error 1
make[2]: *** [all] Error 2
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

Particular settings used for this compile can be found at
http://jhbuild.bxlug.be/builds/2006-06-13-0007/ .