Bug 1434630 - use proper logging framework instead of println. r=kats

This makes webrender much less verbose in release builds, and also
feeds all printing through a single managed point. This is intended
to reduce the amount of crashes we get from stdout becoming unavailable
on users' machines.

gfx/webrender_bindings/src/bindings.rs

@@ -456,10 +456,9 @@ fn get_proc_address(glcontext_ptr: *mut c_void,
     let symbol_name = CString::new(name).unwrap();
     let symbol = unsafe { get_proc_address_from_glcontext(glcontext_ptr, symbol_name.as_ptr()) };
 
-    // For now panic, not sure we should be though or if we can recover
     if symbol.is_null() {
         // XXX Bug 1322949 Make whitelist for extensions
-        println!("Could not find symbol {:?} by glcontext", symbol_name);
+        warn!("Could not find symbol {:?} by glcontext", symbol_name);
     }
 
     symbol as *const _
@@ -564,7 +563,7 @@ pub extern "C" fn wr_renderer_render(renderer: &mut Renderer,
         Ok(_) => true,
         Err(errors) => {
             for e in errors {
-                println!(" Failed to render: {:?}", e);
+                warn!(" Failed to render: {:?}", e);
                 let msg = CString::new(format!("wr_renderer_render: {:?}", e)).unwrap();
                 unsafe {
                     gfx_critical_note(msg.as_ptr());
@@ -836,7 +835,7 @@ pub extern "C" fn wr_window_new(window_id: WrWindowId,
 
     let version = gl.get_string(gl::VERSION);
 
-    println!("WebRender - OpenGL version new {}", version);
+    info!("WebRender - OpenGL version new {}", version);
 
     let workers = unsafe {
         Arc::clone(&(*thread_pool).0)
@@ -879,7 +878,7 @@ pub extern "C" fn wr_window_new(window_id: WrWindowId,
     let (renderer, sender) = match Renderer::new(gl, notifier, opts) {
         Ok((renderer, sender)) => (renderer, sender),
         Err(e) => {
-            println!(" Failed to create a Renderer: {:?}", e);
+            warn!(" Failed to create a Renderer: {:?}", e);
             let msg = CString::new(format!("wr_window_new: {:?}", e)).unwrap();
             unsafe {
                 gfx_critical_note(msg.as_ptr());
@@ -1323,7 +1322,7 @@ pub extern "C" fn wr_api_capture(
             file.write(revision).unwrap();
         }
         Err(e) => {
-            println!("Unable to create path '{:?}' for capture: {:?}", path, e);
+            warn!("Unable to create path '{:?}' for capture: {:?}", path, e);
             return
         }
     }

gfx/webrender_bindings/src/lib.rs

@@ -10,6 +10,8 @@ extern crate app_units;
 extern crate gleam;
 extern crate rayon;
 extern crate thread_profiler;
+
+#[macro_use]
 extern crate log;
 
 #[cfg(target_os = "windows")]