clover: Require libelf

v2: test for libelf once, check in both radeon and clover

CC: Tom Stellard <tom@stellard.net>
CC: Emil Velikov <emil.l.velikov@gmail.com>
CC: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
1 file changed