This fixes the following error message seen when compiling against
glibc 2.36:
from scan/scan_httpdate.c:3:
include/sys/cdefs.h:338:65: error: macro "__has_attribute" requires an identifier
338 | #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__deprecated__)
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>