Optimize travis build

.travis.yml

@@ -1,18 +1,40 @@
 language: go
+
 go:
   - '1.8'
   - '1.9'
   - '1.10'
   - '1.11'
   - tip
+
 env:
   - VIPS_VERSION=8.4.6
   - VIPS_VERSION=8.5.8
+
+cache: apt
+
 install:
   - sudo apt-get -qq update
   - sudo apt-get install -y build-essential libxml2-dev libfftw3-dev gobject-introspection libglib2.0-dev libwebp-dev libgif-dev
   - wget https://github.com/jcupitt/libvips/releases/download/v$VIPS_VERSION/vips-$VIPS_VERSION.tar.gz
   - tar -xzvf vips-$VIPS_VERSION.tar.gz
-  - pushd vips-$VIPS_VERSION && ./configure --prefix=/usr && make && sudo make install && popd
+  - pushd vips-$VIPS_VERSION
+  - >
+    ./configure
+    --prefix=/usr
+    --without-python
+    --without-gsf
+    --without-orc
+    --disable-debug
+    --disable-dependency-tracking
+    --disable-static
+    --enable-silent-rules
+    --enable-gtk-doc-html=no
+    --enable-gtk-doc=no
+    --enable-pyvips8=no
+  - make
+  - sudo make install
+  - popd
+
 script:
   - CGO_LDFLAGS_ALLOW="-s|-w" go build