ocp-index for 4.02

Thanks a lot to Peter Zotov (@whitequark) for the port. Proper compat will
be made upstream, but I really don't have time now, and this is
the easiest way to ocp-index on 4.02 for the users.
Fix ocp-build / typerex conflicts
Add ocamlnet 3.7.5
ocamlnet < 3.7.5 is not compatible with ocaml 4.02 at runtime
config-file depends on camlp4.
ocamlscript requires camlp4
schoca requires camlp4
missinglib requires camlp4
mysql requires camlp4
integration1d requires camlp4
xstrp4 requires camlp4
Merge pull request #2565 from AltGr/ocp-index-402

Enable ocp-indent,index on 4.02
Merge pull request #2577 from yallop/xstrp4-camlp4

xstrp4 requires camlp4
Merge pull request #2576 from yallop/mysql-camlp4

mysql requires camlp4
Merge pull request #2575 from yallop/integration1d-camlp4

integration1d requires camlp4
Merge pull request #2574 from yallop/missinglib-camlp4

missinglib requires camlp4
Merge pull request #2572 from yallop/ocamlscript-camlp4

ocamlscript requires camlp4
Merge pull request #2573 from yallop/camlp4-schoca

schoca requires camlp4
Merge pull request #2571 from yallop/config-file-camlp4

config-file depends on camlp4.
Merge pull request #2566 from jpdeplaix/master

Add ocamlnet 3.7.5