Remove test_ffi and don't build mp4parse_capi as a dynamic library

These changes are necessary for conveniently vendoring into the
mozilla-central tree since test_ffi requires a dynamic library to avoid
duplicate symbols in the final binary, but certain builds fail in
mozilla-central if the vendored in crates build as dynamic libraries.

Since there is currently no way to parametrically disable building as a
dynamic library via cargo, we will remove test_ffi and rely on the builds
in the mozilla-central tree to alert us to API-breaking changes.

Author: baumanj

Cargo.toml

@@ -2,7 +2,6 @@
 members = [
     "mp4parse",
     "mp4parse_capi",
-    "test_ffi",
 ]
 
 [profile.release]

README.md

@@ -17,10 +17,6 @@ API is intended to wrap the rust parser. As such, features should primarily
 be implemented in the rust parser and exposed via the C API, rather than the C
 API implementing features on its own.
 
-`test_ffi` builds and links `test_ffi/src/test.cc` into a small Rust test
-harness in `test_ffi/src/main.rs` that verifies the C API against the
-generated `mp4parse.h`.
-
 ## Tests
 
 Test coverage comes from several sources:

mp4parse_capi/Cargo.toml

@@ -19,9 +19,6 @@ exclude = [
   "*.mp4",
 ]
 
-[lib]
-crate-type = ["lib", "cdylib"]
-
 [badges]
 travis-ci = { repository = "https://github.com/mozilla/mp4parse-rust" }