src: add xfree and use it

This patch adds xfree, a replacement of free that accepts
const pointers. This helps to remove ugly castings that you usually
need to calm down gcc.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/internal.h b/src/internal.h
index d1c7690..4d39660 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -55,6 +55,8 @@ const char *nft_verdict2str(uint32_t verdict);
 int nft_str2verdict(const char *verdict);
 int nft_get_value(enum nft_type type, void *val, void *out);
 
+void xfree(const void *ptr);
+
 struct expr_ops;
 
 struct nft_rule_expr {