b=1043075 revert to no hostbz2 when --with-system-bz2 r=glandium

--HG--
extra : rebase_source : 4d7c0bed8afe7c6edd5b39ca4f971667df35c139

other-licenses/bsdiff/moz.build

@@ -10,9 +10,10 @@ HOST_SOURCES += [
 
 HOST_PROGRAM = 'mbsdiff'
 
-HOST_USE_LIBS += [
-    'hostbz2',
-]
+if not CONFIG['MOZ_NATIVE_BZ2']:
+    HOST_USE_LIBS += [
+        'hostbz2',
+    ]
 
 LOCAL_INCLUDES += [
     '/toolkit/mozapps/update/updater',