[infer][PR] Update OCaml to 4.09 in Travis

Summary:
Lets see if it breaks anything.
Pull Request resolved: https://github.com/facebook/infer/pull/1154

Reviewed By: ngorogiannis

Differential Revision: D21553843

Pulled By: jvillard

fbshipit-source-id: e201b8d30

.travis.yml

@@ -1,6 +1,6 @@
 language: c
 env:
-  - OCAML_VERSION=4.08.1
+  - OCAML_VERSION=4.09.1 OPAM_VERSION=2.0.7
 cache:
   directories:
     - ${HOME}/.opam
@@ -20,13 +20,14 @@ addons:
       - pkg-config
       - sqlite
 before_install:
-  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then ARCH="darwin"; else ARCH="linux"; fi
+  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then ARCH="macos"; else ARCH="linux"; fi
   - if [ "$TRAVIS_OS_NAME" = "osx" ]; then export PATH="/usr/bin:${PATH}"; fi
-  - wget -O ${HOME}/opam https://github.com/ocaml/opam/releases/download/2.0.3/opam-2.0.3-x86_64-${ARCH}
+  - wget -O ${HOME}/opam https://github.com/ocaml/opam/releases/download/${OPAM_VERSION}/opam-${OPAM_VERSION}-x86_64-${ARCH}
   - chmod +x ${HOME}/opam
   - export PATH=${HOME}:${PATH}
   - export OPAMYES=1
   - export OPAMJOBS=2
+  - export INFER_OPAM_SWITCH="ocaml-variants.${OCAML_VERSION}+flambda"
   - if [ "$TRAVIS_OS_NAME" = "osx" ]; then export OPAMEXTERNALSOLVER=$(which aspcud); fi
   - opam init --compiler=${OCAML_VERSION} --disable-sandboxing
   - eval $(opam env)

build-infer.sh

@@ -55,7 +55,7 @@ USER_OPAM_SWITCH=no
 
 ORIG_ARGS="$*"
 
-while [[ $# > 0 ]]; do
+while [[ $# -gt 0 ]]; do
   opt_key="$1"
   case $opt_key in
     all)