expr: Add const qualifiers to *2str translation arrays

Add const qualifiers to the "to string" translation arrays used by
various *2str() functions.

This fixes GCC warnings such as the following when compiling with
-Wwrite-strings:

  expr/byteorder.c:176:25: warning: initialization discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]

In order to catch these in the future, also add -Wwrite-strings to
default CFLAGS.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/expr/dynset.c b/src/expr/dynset.c
index 20a5004..f7b99ea 100644
--- a/src/expr/dynset.c
+++ b/src/expr/dynset.c
@@ -258,7 +258,7 @@ nftnl_expr_dynset_export(char *buf, size_t size,
 	return nftnl_buf_done(&b);
 }
 
-static char *op2str_array[] = {
+static const char *op2str_array[] = {
 	[NFT_DYNSET_OP_ADD]		= "add",
 	[NFT_DYNSET_OP_UPDATE] 		= "update",
 };