Update testargv.c to work on older compilers, added 16-bit .exe of it.

tests/testargv.c

@@ -1,20 +1,23 @@
-#include <stdio.h>
-
-int main(int argc, char **argv, char **envp) {
-    int i;
-
-    printf("Command line: (argc == %d)\n", argc);
-    for (i = 0; i <= argc; i++) {
-        printf("argv[%d] = '%s'\n", i, argv[i]);
-    } // for
-
-    printf("\nEnvironment:\n");
-    for (i = 0; envp[i]; i++) {
-        printf("envp[%d] = '%s'\n", i, envp[i]);
-    } // for
-
-    return 0;
-} // main
-
-// end of testargv.c ...
-
+#include <stdio.h>
+
+extern char **environ;
+
+int main(int argc, char **argv) {
+    int i;
+    char **envp = environ;
+
+    printf("Command line: (argc == %d)\n", argc);
+    for (i = 0; i <= argc; i++) {
+        printf("argv[%d] = '%s'\n", i, argv[i] ? argv[i] : "(null)");
+    } // for
+
+    printf("\nEnvironment:\n");
+    for (i = 0; envp[i]; i++) {
+        printf("envp[%d] = '%s'\n", i, envp[i] ? envp[i] : "(null)");
+    } // for
+
+    return 0;
+} // main
+
+// end of testargv.c ...
+