build: resolve compile abort in libxt_limit on RHEL5

libxt_limit.c: In function 'print_rate':
	libxt_limit.c:124: error: 'INFINITY' undeclared (first use in
	this function)

The default mode of glibc-2.15's <features.h> sets
"-D_POSIX_C_SOURCE=200809L", and therefore "-D_ISOC99_SOURCE". However,
on þe olde RHEL 5's glibc-2.5, it only has "-D_POSIX_C_SOURCE=200112L".

Explicitly draw in the definition of INFINITY by always defining
_ISOC99_SOURCE. By doing this, we are moving off of the default set, so
_BSD_SOURCE also needs to be explicitly set to get at IFNAMSIZ that is
used in xt_hashlimit.h.

Signed-off-by: Jan Engelhardt <jengelh@inai.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2 files changed