t/*: rearrange tests into numbered directories.

It was getting way too ad-hoc in there.  Let's reorganize the tests so that
there's a good, obvious, suggested sequence to run them in.

t/110-compile/hello.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main()
+{
+    printf("hello, world!\n");
+    return 0;
+}