Allow tophide to compile with ocaml < 4.02.0

4.02.0 will need an update due to change to Outcometree.Osig_exception.
Note; tophide is used by mikmatch when it is run in the toplevel.
mikmatch for ocaml 4.01.0

attempts to make pcre backend optional and compiles str by default
revert change - need to use and updated package

will add 1.0.2 instead
add tophide 1.0.2 for ocaml >=4.00 & < 4.02

note; made up version which isn't released upstream (uses commit hash)
fix syntax for optional install and add patch

the patch makes mikmatch_str depend on str rather than pcre so it can be
installed separately.
Merge pull request #2194 from andrewray/mikmatch

Mikmatch 1.0.7 for ocaml 4.01