package/ci: don't exit if iOS build *doesn't* fail.

That was a brainfart.

package/ci/travis-ios-simulator.sh

@@ -31,7 +31,7 @@ cmake .. \
     -DTESTSUITE_TARGET_XCTEST=ON \
     -DWITH_INTERCONNECT=OFF \
     -G Xcode
-cmake --build . --config Release --target install | xcpretty && exit ${PIPESTATUS[0]}
+set -o pipefail && cmake --build . --config Release --target install | xcpretty
 cd ../..
 
 # Crosscompile Magnum
@@ -59,7 +59,7 @@ cmake .. \
     -DBUILD_TESTS=ON \
     -DBUILD_GL_TESTS=ON \
     -G Xcode
-cmake --build . --config Release | xcpretty && exit ${PIPESTATUS[0]}
+set -o pipefail && cmake --build . --config Release | xcpretty
 # TODO: find a better way to avoid
 # Library not loaded: /System/Library/Frameworks/OpenGLES.framework/OpenGLES
 # error