Add ios flags to ios invocations

Author: alexcrichton

.travis.yml

@@ -50,12 +50,16 @@ matrix:
     - env: TARGET=aarch64-unknown-linux-gnu
     - os: osx
       osx_image: xcode8.2
-      env: TARGET=i386-apple-ios CARGO_TARGET_I386_APPLE_IOS_RUNNER=$HOME/runtest
+      env: TARGET=i386-apple-ios
+           CARGO_TARGET_I386_APPLE_IOS_RUNNER=$HOME/runtest
+           RUSTFLAGS=-Clink-arg=-mios-simulator-version-min=7.0
       before_install:
         rustc ./ci/ios/deploy_and_run_on_ios_simulator.rs -o $HOME/runtest
     - os: osx
       osx_image: xcode8.2
-      env: TARGET=x86_64-apple-ios CARGO_TARGET_X86_64_APPLE_IOS_RUNNER=$HOME/runtest
+      env: TARGET=x86_64-apple-ios
+           CARGO_TARGET_X86_64_APPLE_IOS_RUNNER=$HOME/runtest
+           RUSTFLAGS=-Clink-arg=-mios-simulator-version-min=7.0
       before_install:
         rustc ./ci/ios/deploy_and_run_on_ios_simulator.rs -o $HOME/runtest
     - env: TARGET=x86_64-rumprun-netbsd