Travis: Use curl rather than wget for Mac SDK

.travis.yml

@@ -52,7 +52,7 @@ install:
 before_script:
     - unset CC; unset CXX
     - mkdir -p depends/SDKs depends/sdk-sources
-    - if [ -n "$OSX_SDK" -a ! -f depends/sdk-sources/MacOSX${OSX_SDK}.sdk.tar.gz ]; then wget $SDK_URL/MacOSX${OSX_SDK}.sdk.tar.gz -O depends/sdk-sources/MacOSX${OSX_SDK}.sdk.tar.gz; fi
+    - if [ -n "$OSX_SDK" -a ! -f depends/sdk-sources/MacOSX${OSX_SDK}.sdk.tar.gz ]; then curl $SDK_URL/MacOSX${OSX_SDK}.sdk.tar.gz -o depends/sdk-sources/MacOSX${OSX_SDK}.sdk.tar.gz; fi
     - if [ -n "$OSX_SDK" -a -f depends/sdk-sources/MacOSX${OSX_SDK}.sdk.tar.gz ]; then tar -C depends/SDKs -xf depends/sdk-sources/MacOSX${OSX_SDK}.sdk.tar.gz; fi
     - make $MAKEJOBS -C depends HOST=$HOST $DEP_OPTS
 script: