tool_getparam: clear sensitive arguments better

curl attempts to clear some flags to hide them from snooping neighbors
(on platforms where it works). For example the credentials provided with
-u. Previously it would only do that if there was a space between the
option and the credentials as in "-u joe:s3cr3t" but not when done
without a separating space as in "-ujoe:s3cr3t".

This addresses that previous shortcoming.

Reported-by: kayrus on github
Fixes #16396
Closes #16401

src/tool_getparam.h

@@ -361,7 +361,8 @@ const struct LongShort *findlongopt(const char *opt);
 const struct LongShort *findshortopt(char letter);
 
 ParameterError getparameter(const char *flag, char *nextarg,
-                            argv_item_t cleararg,
+                            argv_item_t cleararg1,
+                            argv_item_t cleararg2,
                             bool *usedarg,
                             struct GlobalConfig *global,
                             struct OperationConfig *operation);