Weird that this was set to not enable C++, but I suspect it is the
reason why the C++11 compiler flag isn't being added to resolve this:
```
warning: harfbuzz/src/hb-meta.hh:41:18: warning: variadic templates are a C++11 extension [-Wc++11-extensions]
warning: template<typename... Ts> struct _hb_void_t { typedef void type; };
```
This commit more cleanly separates the load from the render flags,
and fixes up the render call; at some point this got messed up such
that we'd never end up with freetype returning subpixel format data
(LCD) and instead we'd only ever get grayscale data.
With that fixed, it's apparent that the colorization of the glyph
data was wonky in the shader so this commit also cleans this up.
refs: #320
refs: #121
`cargo test --release --all` was broken by a recent update.
Interesting that it only broke when building tests.
Regardless: these deps should probably have always been required,
so this is a legit change.
Forgetting to update the submodules is a commonly reported build
issue with an obscure error message:
```
CMake Error: The source directory "/home/USER/wezterm/target/debug/build/freetype-430fe24cb64c561c/out/zlib-src/zlib" does not appear to contain CMakeLists.txt.
```
this teaches the build.rs machinery to run the submodule update
if it looks like it is needed.
Streamline the travis deploy builds; when TRAVIS_TAG is set
we'll run `--release` builds.
Don't error out in fontconfig/build.rs if fontconfig is not
installed. This makes it possible to `cargo test --all` again
on the mac at the cost of potentially making it harder to troubleshoot
problems with not having fontconfig installed on linux.
However: the get-deps script is responsible for installing that.
This is primarily for macos where the default freetype
installation is unable to render color emoji, but should also
help make things more consistent across the various platforms.
It's a little bit awkward on linux because the font-loader crate
pulls in the now-conflicting servo-font* crates. I've disabled
font-loader on linux systems; it's just calling fontconfig under
the covers anyway.
