Remove build_linux_headless

servo/servo#8641 made headless go away, so we don't need a separate environment for it any more.
servo · bors-servo · May 14, 2016 · May 11, 2016 · May 13, 2016 · May 14, 2016
commit f995a77e6884ddce8d4e115f4b70a1ffd3f81208
diff --git a/buildbot/master/files/config/environments.py b/buildbot/master/files/config/environments.py
@@ -59,10 +59,6 @@ def __add__(self, other):
     'SHELL': '/bin/bash',
 })
 
-build_linux_headless = build_linux + Environment({
-    'SERVO_HEADLESS': '1',
-})
-
 build_android = build_linux + Environment({
     'ANDROID_NDK': '{{ common.servo_home }}/android/ndk/current/',
     'ANDROID_SDK': '{{ common.servo_home }}/android/sdk/current/',

diff --git a/buildbot/master/files/config/master.cfg b/buildbot/master/files/config/master.cfg
@@ -135,8 +135,8 @@ class DynamicServoBuilder(util.BuilderConfig):
 
 
 c['builders'] = [
-    DynamicServoBuilder("linux-dev", LINUX_SLAVES, envs.build_linux_headless),
-    DynamicServoBuilder("linux-rel", LINUX_SLAVES, envs.build_linux_headless),
+    DynamicServoBuilder("linux-dev", LINUX_SLAVES, envs.build_linux),
+    DynamicServoBuilder("linux-rel", LINUX_SLAVES, envs.build_linux),
     DynamicServoBuilder("android", CROSS_SLAVES, envs.build_android),
     DynamicServoBuilder("arm32", CROSS_SLAVES, envs.build_arm32),
     DynamicServoBuilder("arm64", CROSS_SLAVES, envs.build_arm64),