Change glutin headless mode to be a build config, as it breaks some Linux distros linking to both.

The majority of this change is simply re-arranging the code in the glutin port
so that the windowed/headless code is configured at build time rather
than runtime. There shouldn't be any functional difference as a result of this change.

components/servo/Cargo.lock

@@ -335,7 +335,7 @@ dependencies = [
 [[package]]
 name = "glutin"
 version = "0.0.2"
-source = "git+https://github.com/servo/glutin?ref=servo#db27370a1cbafcbfcaeee52a44076a61b3e0573c"
+source = "git+https://github.com/servo/glutin?ref=servo#ec6b4d0fff12ef607db422508ae005ba91406f5b"
 dependencies = [
  "android_glue 0.0.1 (git+https://github.com/servo/android-rs-glue?ref=servo)",
  "cocoa 0.1.1 (git+https://github.com/servo/rust-cocoa)",

components/servo/Cargo.toml

@@ -27,8 +27,10 @@ path = "../../tests/contenttest.rs"
 harness = false
 
 [features]
-default = ["glutin_app"]
+default = ["glutin_app", "window"]
 glfw = ["glfw_app"]
+window = ["glutin_app/window"]
+headless = ["glutin_app/headless"]
 
 [dependencies.compositing]
 path = "../compositing"

components/util/opts.rs

@@ -11,7 +11,6 @@ use geom::scale_factor::ScaleFactor;
 use geom::size::TypedSize2D;
 use layers::geometry::DevicePixel;
 use getopts;
-use std::borrow::ToOwned;
 use std::collections::HashSet;
 use std::cmp;
 use std::io;
@@ -20,12 +19,6 @@ use std::os;
 use std::ptr;
 use std::rt;
 
-#[deriving(Clone, Copy)]
-pub enum RenderApi {
-    OpenGL,
-    Mesa,
-}
-
 /// Global flags for Servo, currently set on the command line.
 #[deriving(Clone)]
 pub struct Opts {
@@ -113,8 +106,6 @@ pub struct Opts {
     /// Whether to show an error when display list geometry escapes flow overflow regions.
     pub validate_display_list_geometry: bool,
 
-    pub render_api: RenderApi,
-
     /// A specific path to find required resources (such as user-agent.css).
     pub resources_path: Option<String>,
 }
@@ -183,7 +174,6 @@ pub fn default_opts() -> Opts {
         dump_flow_tree: false,
         validate_display_list_geometry: false,
         profile_tasks: false,
-        render_api: RenderApi::OpenGL,
         resources_path: None,
     }
 }
@@ -303,15 +293,6 @@ pub fn from_cmdline_args(args: &[String]) -> bool {
         }
     };
 
-    let render_api = match opt_match.opt_str("r").unwrap_or("gl".to_owned()).as_slice() {
-        "mesa" => RenderApi::Mesa,
-        "gl" => RenderApi::OpenGL,
-        _ => {
-            args_fail("Unknown render api specified");
-            return false;
-        }
-    };
-
     let opts = Opts {
         urls: urls,
         n_paint_threads: n_paint_threads,
@@ -337,7 +318,6 @@ pub fn from_cmdline_args(args: &[String]) -> bool {
         enable_text_antialiasing: !debug_options.contains(&"disable-text-aa"),
         dump_flow_tree: debug_options.contains(&"dump-flow-tree"),
         validate_display_list_geometry: debug_options.contains(&"validate-display-list-geometry"),
-        render_api: render_api,
         resources_path: opt_match.opt_str("resources-path"),
     };