Added 'const' to arguments in get_one_option and find_typeset()

One should not change the program arguments!
This change also reduces warnings from the icc compiler.

Almost all changes are just syntax changes (adding const to
'get_one_option function' declarations).

Other changes:
- Added a few cast of 'argument' from 'const char*' to 'char *'. This
  was mainly in calls to 'external' functions we don't have control of.
- Ensure that all reset of 'password command line argument' are similar.
  (In almost all cases it was just adding a comment and a cast)
- In mysqlbinlog.cc and mysqld.cc there was a few cases that changed
  the command line argument. These places where changed to instead allocate
  the option in a MEM_ROOT to avoid changing the argument. Some of this
  code was changed to ensure that different programs did parsing the
  same way. Added a test case for the changes in mysqlbinlog.cc
- Changed a few variables that took their value from command line options
  from 'char *' to 'const char *'.

client/mysqlbinlog.cc

@@ -96,6 +96,7 @@ static FILE *result_file;
 static char *result_file_name= 0;
 static const char *output_prefix= "";
 static char **defaults_argv= 0;
+static MEM_ROOT glob_root;
 
 #ifndef DBUG_OFF
 static const char *default_dbug_option = "d:t:o,/tmp/mariadb-binlog.trace";
@@ -1889,6 +1890,7 @@ static void cleanup()
   my_free(const_cast<char*>(dirname_for_local_load));
   my_free(start_datetime_str);
   my_free(stop_datetime_str);
+  free_root(&glob_root, MYF(0));
 
   delete binlog_filter;
   delete glob_description_event;
@@ -1957,7 +1959,7 @@ static my_time_t convert_str_to_timestamp(const char* str)
 
 
 extern "C" my_bool
-get_one_option(const struct my_option *opt, char *argument, const char *)
+get_one_option(const struct my_option *opt, const char *argument, const char *)
 {
   bool tty_password=0;
   switch (opt->id) {
@@ -1981,10 +1983,15 @@ get_one_option(const struct my_option *opt, char *argument, const char *)
       argument= (char*) "";                     // Don't require password
     if (argument)
     {
+      /*
+        One should not really change the argument, but we make an
+        exception for passwords
+      */
       my_free(pass);
-      char *start=argument;
+      char *start= (char*) argument;
       pass= my_strdup(PSI_NOT_INSTRUMENTED, argument,MYF(MY_FAE));
-      while (*argument) *argument++= 'x';		/* Destroy argument */
+      while (*argument)
+        *(char*)argument++= 'x';		/* Destroy argument */
       if (*start)
         start[1]=0;				/* Cut length of argument */
     }
@@ -2035,46 +2042,46 @@ get_one_option(const struct my_option *opt, char *argument, const char *)
   case OPT_REWRITE_DB:    // db_from->db_to
   {
     /* See also handling of OPT_REPLICATE_REWRITE_DB in sql/mysqld.cc */
-    char* ptr;
-    char* key= argument;  // db-from
-    char* val;            // db-to
+    const char* ptr;
+    const char* key= argument;  // db-from
+    const char* val;            // db-to
 
-    // Where key begins
+    // Skipp pre-space in key
     while (*key && my_isspace(&my_charset_latin1, *key))
       key++;
 
     // Where val begins
-    if (!(ptr= strstr(argument, "->")))
+    if (!(ptr= strstr(key, "->")))
     {
-      sql_print_error("Bad syntax in rewrite-db: missing '->'!\n");
+      sql_print_error("Bad syntax in rewrite-db: missing '->'\n");
       return 1;
     }
     val= ptr + 2;
+
+    // Skip blanks at the end of key
+    while (ptr > key && my_isspace(&my_charset_latin1, ptr[-1]))
+      ptr--;
+
+    if (ptr == key)
+    {
+      sql_print_error("Bad syntax in rewrite-db: empty FROM db\n");
+      return 1;
+    }
+    key= strmake_root(&glob_root, key, (size_t) (ptr-key));
+
+    /* Skipp pre space in value */
     while (*val && my_isspace(&my_charset_latin1, *val))
       val++;
 
-    // Write \0 and skip blanks at the end of key
-    *ptr-- = 0;
-    while (my_isspace(&my_charset_latin1, *ptr) && ptr > argument)
-      *ptr-- = 0;
-
-    if (!*key)
+    // Value ends with \0 or space
+    for (ptr= val; *ptr && !my_isspace(&my_charset_latin1, *ptr) ; ptr++)
+    {}
+    if (ptr == val)
     {
-      sql_print_error("Bad syntax in rewrite-db: empty db-from!\n");
-      return 1;
-    }
-
-    // Skip blanks at the end of val
-    ptr= val;
-    while (*ptr && !my_isspace(&my_charset_latin1, *ptr))
-      ptr++;
-    *ptr= 0;
-
-    if (!*val)
-    {
-      sql_print_error("Bad syntax in rewrite-db: empty db-to!\n");
+      sql_print_error("Bad syntax in rewrite-db: empty TO db\n");
       return 1;
     }
+    val= strmake_root(&glob_root, val, (size_t) (ptr-val));
 
     binlog_filter->add_db_rewrite(key, val);
     break;
@@ -3045,6 +3052,8 @@ int main(int argc, char** argv)
   load_defaults_or_exit("my", load_groups, &argc, &argv);
   defaults_argv= argv;
 
+  init_alloc_root(PSI_NOT_INSTRUMENTED, &glob_root, 1024, 0, MYF(0));
+
   if (!(binlog_filter= new Rpl_filter))
   {
     error("Failed to create Rpl_filter");