cppcheck: Use inline suppression for ffsl()

We define our own ffsl() as a weak symbol, in case our C library doesn't
include it.  On glibc systems which *do* include it, this causes a cppcheck
warning because unsurprisingly our version doesn't pick the same argument
names.  Convert the suppression for this into an inline suppression.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

util.h

@@ -217,6 +217,7 @@ struct ipv6_opt_hdr {
 	 */
 } __attribute__((packed));	/* required for some archs */
 
+/* cppcheck-suppress funcArgNamesDifferent */
 __attribute__ ((weak)) int ffsl(long int i) { return __builtin_ffsl(i); }
 void __openlog(const char *ident, int option, int facility);
 void passt_vsyslog(int pri, const char *format, va_list ap);