Use --jobs 3 when updating submodules

.travis.yml

@@ -17,6 +17,9 @@ language: cpp
 
 compiler: gcc
 
+git:
+  submodules: false
+
 addons:
   apt:
     packages:
@@ -80,7 +83,7 @@ matrix:
       after_script: true
 
       install:
-      - git submodule update --init
+      - git submodule update --init --jobs 3
 
       script:
       - mkdir __build && cd __build
@@ -98,7 +101,7 @@ matrix:
       after_script: true
 
       install:
-      - git submodule update --init
+      - git submodule update --init --jobs 3
 
       script:
       - mkdir __build && cd __build
@@ -121,6 +124,7 @@ matrix:
 
 before_install:
   # Fetch the scripts to do the actual building/testing.
+  - git submodule update --init --jobs 3
   - |
     wget "https://raw.githubusercontent.com/boostorg/release-tools/develop/ci_boost_common.py" -P ..
     wget "https://raw.githubusercontent.com/boostorg/release-tools/develop/${SCRIPT}.py" -P ..