tool_getparam: repair cleanarg

Regression since 9e5669f.

Make sure the "cleaning" of command line arguments is done on the
original argv[] pointers. As a bonus, it also exits better on out of
memory error.

Reported-by: Litter White
Fixes #9128
Closes #9130

src/tool_getparam.h

@@ -54,7 +54,8 @@ typedef enum {
 struct GlobalConfig;
 struct OperationConfig;
 
-ParameterError getparameter(const char *flag, char *nextarg, bool *usedarg,
+ParameterError getparameter(const char *flag, char *nextarg, char *clearthis,
+                            bool *usedarg,
                             struct GlobalConfig *global,
                             struct OperationConfig *operation);