libgit2: add a dependency on openssl

If this dependency is missing its possible that openssl won't be built
before libgit2 is built and then we won't have git support over SSL
which leaves out a lot of git repos.

recipes-deps/libgit2/libgit2.inc

@@ -2,7 +2,7 @@ SUMMARY = "the Git linkable library"
 HOMEPAGE = "http://libgit2.github.com/"
 LICENSE = "GPL-2.0-with-linking-exception"
 
-DEPENDS = "zlib"
+DEPENDS = "openssl zlib"
 
 inherit cmake