clamav: Fix building on ARM.

Disable using fanotify:

  CC     fan.o
In file included from fan.c:38:
fan-syscalllib.h:14:3: error: #error "System call numbers not defined for this architecture"
In file included from fan.c:38:
fan-syscalllib.h: In function 'fanotify_init':
fan-syscalllib.h:19: error: '__NR_fanotify_init' undeclared (first use in this function)
fan-syscalllib.h:19: error: (Each undeclared identifier is reported only once
fan-syscalllib.h:19: error: for each function it appears in.)
fan-syscalllib.h: In function 'fanotify_mark':
fan-syscalllib.h:25: error: '__NR_fanotify_mark' undeclared (first use in this function)
make[3]: *** [fan.o] Error 1
make[3]: Leaving directory `/usr/src/clamav-0.98/clamd'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `/usr/src/clamav-0.98'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/usr/src/clamav-0.98'
make: *** [/usr/src/log/clamav-0.98] Error 2