servo: Merge #4642 - Minor fix to Arch developer setup instructions (from martine:patch-1)

Source-Repo: https://github.com/servo/servo
Source-Revision: c70197b48d64a3228c6d0cffafa1671a843fcc9d

servo/README.md

@@ -49,7 +49,7 @@ popd
 On Arch Linux:
 
 ``` sh
-sudo pacman -S base-devel git python2 python2-virtualenv mesa ttf-font cmake bzip2
+sudo pacman -S --needed base-devel git python2 python2-virtualenv mesa ttf-font cmake bzip2
 ```
 
 Cross-compilation for Android: