Improve lib template on Travis

This commit contains changes on the generated lib template to build
cross-platform libs. With this changes, I was able to setup a [Travis]
build with GitHub [Releases] of a cross-platform lib.

It is not possible yet to build a different crate type only using
command line args. It requires a modification on `Cargo.toml` to include
new types of library outputs. I've already opened an issue on [cargo](rust-lang/cargo#6160) to see what should be the case here.

Meanwhile, lib authors must change `Cargo.toml` and include the extra
`crate-type` attribute with all the libs. Sadly, this also means that
`LTO` optimisation is not available if the lib uses `lib` or `rlib`
attributes.

To avoid modifying the `Cargo.toml`, the sugestion would be that on a
future PR we could add to the deploy script a modification on the
`Cargo.toml` manifest to include the corresponding crate-type, and only
such crate type for that target. This means we would be able to bring
LTO and output smaller libs.

Realated to:
- yoshuawuyts#11

[Travis]: https://travis-ci.org/bltavares/rust-over-jna-example/builds/439439854
[Releases]: https://github.com/bltavares/rust-over-jna-example/releases/tag/initial

templates/lib/before_deploy.sh

@@ -6,7 +6,8 @@ set -ex
 
 main() {
   local src=$(pwd) \
-    stage=
+        stage= \
+        linking_args=
 
   case $TRAVIS_OS_NAME in
     linux)
@@ -19,8 +20,29 @@ main() {
 
   test -f Cargo.lock || cargo generate-lockfile
 
-  cross rustc --bin $PKG_NAME --target $TARGET --release -- -C lto
-  cp target/$TARGET/release/$PKG_NAME $stage/
+  # TODO: combine with -C lto
+  case $TYPE in
+      static)
+          linking_args="--crate-type staticlib"
+          ;;
+      *)
+          linking_args="--crate-type cdylib"
+          ;;
+  esac
+
+  cross rustc --lib --target $TARGET --release -- $linking_args
+
+  case $TYPE-$TRAVIS_OS_NAME in
+      static-*)
+          cp target/$TARGET/release/lib$PKG_NAME.a $stage/
+          ;;
+      *-osx)
+          cp target/$TARGET/release/lib$PKG_NAME.dylib $stage/
+          ;;
+      *)
+          cp target/$TARGET/release/lib$PKG_NAME.so $stage/
+          ;;
+  esac
 
   cd $stage
   tar czf $src/$CRATE_NAME-$TRAVIS_TAG-$TARGET.tar.gz *

templates/lib/travis.yml

@@ -12,7 +12,7 @@ matrix:
   include:
     - env: TARGET=armv7-unknown-linux-gnueabihf
       rust: nightly
-    - env: TARGET=x86_64-unknown-linux-musl
+    - env: TARGET=x86_64-unknown-linux-musl TYPE=static
       rust: nightly
     - env: TARGET=x86_64-apple-darwin
       rust: nightly