Revert "Use normal stripping"

mozbuild already does equivalent stripping. The +20M install size (but
-10M package size) difference from 54 to 55 must come from somewhere
else.

PKGBUILD

@@ -17,7 +17,7 @@ optdepends=('networkmanager: Location detection via available WiFi networks'
             'libnotify: Notification integration'
             'pulseaudio: Audio support'
             'speech-dispatcher: Text-to-Speech')
-options=(!emptydirs !makeflags)
+options=(!emptydirs !makeflags !strip)
 _repo=https://hg.mozilla.org/mozilla-unified
 source=("hg+$_repo#tag=FIREFOX_${pkgver//./_}_RELEASE"
         $pkgname.desktop firefox-symbolic.svg