Remove depth option from submodule update.

We need `back to the future` sometime, such as merge develop to master.

.travis.yml

@@ -191,7 +191,7 @@ install:
   - git submodule init libs/utility
 
   - git submodule init tools/build
-  - git submodule update --depth 10
+  - git submodule update
 
   - rm -rf libs/fusion
   - mv $TRAVIS_BUILD_DIR libs/fusion

appveyor.yml

@@ -63,7 +63,7 @@ install:
   - git submodule init libs/utility
 
   - git submodule init tools/build
-  - git submodule update --depth 10
+  - git submodule update
   - xcopy /s /e /q %APPVEYOR_BUILD_FOLDER% libs\fusion
   - cmd /c bootstrap
   - b2 headers