Restore 2001/herrmann2 original code

By some chance it was in .gitignore and was entirely missing so I
restored it from the archive.

I also updated the README.md file about the alt (which is the original
in fact) not compiling with clang (something I fixed in the entry
itself) in addition to it might not working in some systems (like 64-bit
systems).

2001/herrmann2/README.md

@@ -75,8 +75,9 @@ diff herrmann2.alt.c herrmann2.orig.c && echo "output matches with original code
 
 ## Alternate code:
 
-If you wish to use the original version that does not work for all platforms,
-you can make use of the [herrmann2.alt.c](herrmann2.alt.c) by running:
+If you wish to use the original version that does not work for all platforms
+(and will not even compile with some versions of clang), you can make use of the
+[herrmann2.alt.c](herrmann2.alt.c) by running:
 
 ```sh
 make alt