CLEANUP: log: make the low_level lf_{ip,port,text,text_len} functions take consts

These ones were abusively relying on variables making it hard to integrate
with const arguments.
diff --git a/include/proto/log.h b/include/proto/log.h
index 3e17733..419e0b3 100644
--- a/include/proto/log.h
+++ b/include/proto/log.h
@@ -150,19 +150,19 @@
  *
  * Return the adress of the \0 character, or NULL on error
  */
-char *lf_text_len(char *dst, const char *src, size_t len, size_t size, struct logformat_node *node);
+char *lf_text_len(char *dst, const const char *src, size_t len, size_t size, const struct logformat_node *node);
 
 /*
  * Write a IP adress to the log string
  * +X option write in hexadecimal notation, most signifant byte on the left
  */
-char *lf_ip(char *dst, struct sockaddr *sockaddr, size_t size, struct logformat_node *node);
+char *lf_ip(char *dst, const struct sockaddr *sockaddr, size_t size, const struct logformat_node *node);
 
 /*
  * Write a port to the log
  * +X option write in hexadecimal notation, most signifant byte on the left
  */
-char *lf_port(char *dst, struct sockaddr *sockaddr, size_t size, struct logformat_node *node);
+char *lf_port(char *dst, const struct sockaddr *sockaddr, size_t size, const struct logformat_node *node);
 
 
 #endif /* _PROTO_LOG_H */
diff --git a/src/log.c b/src/log.c
index dfac121..0c5e1f9 100644
--- a/src/log.c
+++ b/src/log.c
@@ -1053,7 +1053,7 @@
  *
  * Return the adress of the \0 character, or NULL on error
  */
-char *lf_text_len(char *dst, const char *src, size_t len, size_t size, struct logformat_node *node)
+char *lf_text_len(char *dst, const char *src, size_t len, size_t size, const struct logformat_node *node)
 {
 	if (size < 2)
 		return NULL;
@@ -1097,7 +1097,7 @@
 	return dst;
 }
 
-static inline char *lf_text(char *dst, const char *src, size_t size, struct logformat_node *node)
+static inline char *lf_text(char *dst, const char *src, size_t size, const struct logformat_node *node)
 {
 	return lf_text_len(dst, src, size, size, node);
 }
@@ -1106,7 +1106,7 @@
  * Write a IP adress to the log string
  * +X option write in hexadecimal notation, most signifant byte on the left
  */
-char *lf_ip(char *dst, struct sockaddr *sockaddr, size_t size, struct logformat_node *node)
+char *lf_ip(char *dst, const struct sockaddr *sockaddr, size_t size, const struct logformat_node *node)
 {
 	char *ret = dst;
 	int iret;
@@ -1131,7 +1131,7 @@
  * Write a port to the log
  * +X option write in hexadecimal notation, most signifant byte on the left
  */
-char *lf_port(char *dst, struct sockaddr *sockaddr, size_t size, struct logformat_node *node)
+char *lf_port(char *dst, const struct sockaddr *sockaddr, size_t size, const struct logformat_node *node)
 {
 	char *ret = dst;
 	int iret;