[core] mark some more funcs w/ __attribute_pure__

src/http_header.h

@@ -39,6 +39,7 @@ enum http_header_e {
  ,HTTP_HEADER_X_FORWARDED_PROTO = 0x04000000
 };
 
+__attribute_pure__
 enum http_header_e http_header_hkey_get(const char *s, size_t slen);
 
 buffer * http_header_response_get(connection *con, enum http_header_e id, const char *k, size_t klen);

src/stat_cache.c

@@ -53,6 +53,7 @@ typedef struct stat_cache {
 
 
 /* the famous DJB hash function for strings */
+__attribute_pure__
 static uint32_t djbhash(const char *str, const size_t len)
 {
     const unsigned char * const s = (const unsigned char *)str;
@@ -62,6 +63,7 @@ static uint32_t djbhash(const char *str, const size_t len)
 }
 
 
+__attribute_pure__
 static uint32_t hashme(const char *str, const size_t len)
 {
     /* strip highest bit of hash value for splaytree */