Summary:
This is towards getting open source FBOSS to build using fbcode_builder.
iproute2 is one of the dependencies for FBOSS. This patch adds a manifest file
to build the specific version of iproute2 needed for FBOSS.

Additionally, the default git clone depth of 100 is insufficient for the
version of iproute2 FBOSS depends on. Thus, this patch extends the git SCHEMA
to add optional argument depth. The default remains 100.

The usual /configure --prefix does not work for iproute2. Thus, we need to add
a custom builder that:
  - copies sources to build directory, builds, and
  - installs to installed directory using DEST_DIR.
  - it must also explicitly copy include from build dir to install dir

Reviewed By: wez

Differential Revision: D15588809

fbshipit-source-id: ac5eab24134e078d88b85b4be433c78b05ef8ce5