remove depexts for OpenSUSE, RHEL and CentOS
remove depexts for OpenSUSE, RHEL and CentOS

OpenSUSE, RHEL and CentOS don't seem to ship lmdb-devel.
For RHEL and CentOS it is available from EPEL:
http://mirrors.syringanetworks.net/fedora-epel/8/Everything/x86_64/Packages/l/lmdb-devel-0.9.23-2.el8.x86_64.rpm

Is it possible to explain this to depexts ?

seliopou/opam-repository,cakeplus/opam-repository,astrada/opam-repository,c-cube/opam-repository,nberth/opam-repository,emillon/opam-repository,arlencox/opam-repository,mjambon/opam-repository,jonludlam/opam-repository,AltGr/opam-repository,abate/opam-repository,pqwy/opam-repository,hannesm/opam-repository,fpottier/opam-repository,kkirstein/opam-repository,andersfugmann/opam-repository,codinuum/opam-repository,orbitz/opam-repository,astrada/opam-repository,ocaml/opam-repository,AltGr/opam-repository,pirbo/opam-repository,dbuenzli/opam-repository,jonludlam/opam-repository,pqwy/opam-repository,djs55/opam-repository,jhwoodyatt/opam-repository,toots/opam-repository,Chris00/opam-repository,seliopou/opam-repository,talex5/opam-repository,Leonidas-from-XIV/opam-repository,mjambon/opam-repository,Chris00/opam-repository,lefessan/opam-repository,hannesm/opam-repository,dbuenzli/opam-repository,toots/opam-repository,fpottier/opam-repository,c-cube/opam-repository,nberth/opam-repository,yallop/opam-repository,codinuum/opam-repository,andersfugmann/opam-repository,yallop/opam-repository,hakuch/opam-repository,Leonidas-from-XIV/opam-repository,emillon/opam-repository,lefessan/opam-repository,djs55/opam-repository,talex5/opam-repository,kkirstein/opam-repository,jhwoodyatt/opam-repository,pirbo/opam-repository,ocaml/opam-repository