ENH: remove warnings in tests

Tests/LinkLineOrder/Two.c

@@ -1,4 +1,5 @@
 void OneFunc();
+void NoDepZ_func();
 
 void TwoFunc()
 {

Tests/LoadCommand/CMakeCommands/cmTestCommand.c

@@ -13,7 +13,7 @@ typedef struct
 static int InitialPass(void *inf, void *mf, int argc, char *argv[])
 {
   char* file;
-  char* str;
+  const char* str;
   char buffer[1024];
   void *source_file;
   cmLoadedCommandInfo *info = (cmLoadedCommandInfo *)inf;

Tests/LoadCommandOneConfig/CMakeCommands/cmTestCommand.c

@@ -13,7 +13,7 @@ typedef struct
 static int InitialPass(void *inf, void *mf, int argc, char *argv[])
 {
   char* file;
-  char* str;
+  const char* str;
   char buffer[1024];
   void *source_file;
   cmLoadedCommandInfo *info = (cmLoadedCommandInfo *)inf;