Const-ify the world (or at least a good part of it)

This patch adds 'const' tags to a number of Asterisk APIs where they are appropriate (where the API already demanded that the function argument not be modified, but the compiler was not informed of that fact). The list includes:

- CLI command handlers
- CLI command handler arguments
- AGI command handlers
- AGI command handler arguments
- Dialplan application handler arguments
- Speech engine API function arguments

In addition, various file-scope and function-scope constant arrays got 'const' and/or 'static' qualifiers where they were missing.

Review: https://reviewboard.asterisk.org/r/251/



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@196072 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/utils.h

@@ -215,9 +215,9 @@ struct ast_hostent {
 struct hostent *ast_gethostbyname(const char *host, struct ast_hostent *hp);
 
 /*!  \brief Produces MD5 hash based on input string */
-void ast_md5_hash(char *output, char *input);
+void ast_md5_hash(char *output, const char *input);
 /*! \brief Produces SHA1 hash based on input string */
-void ast_sha1_hash(char *output, char *input);
+void ast_sha1_hash(char *output, const char *input);
 
 int ast_base64encode_full(char *dst, const unsigned char *src, int srclen, int max, int linebreaks);