Added program to test command line and environment variable passing.

tests/testargv.c

@@ -0,0 +1,20 @@
+#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 ...
+