Fix gettext dynamic linkage breaking binary builds due to missing dylib

Currently, all the external libraries MacVim links against are
dynamically linked, but so far they are all system libraries or bundled
in /usr/lib, so all users have them installed. When gettext dependency
was added to the Travis build to add localization support, it relied on
an installed libintl.dylib library, usually in /usr/local/lib. This
means users who don't have it installed and open the distributed binary
will see MacVim immediately crash due to a missing dylib.

Instead, statically link against libintl.a instead. This is tricky
because clang stubbornly prefers dynamic libs over static ones if both
exist and you use the "-l" argument. Instead, you have to pass full path
to the static lib for it to link against it. Modify configure.ac to do
so, but because of the full path requirement, it's hard to get
AC_TRY_LINK to work with it, so just manually check for the library's
existence and use that. Hacky but works.

Also, add a check to Travis CI build to make sure we didn't accidentally
introduce third-party dynacmic linkage to the build.
- Add a new test to use objdump to dump out the dependencies, and check
  that we don't have any external third-party linkage (basically any
  dynamic links other than the pre-installed /usr/lib). Have to also
  check for existence of objdump because xcode 7 / macOS 10.11 doesn't
  have it installed.
- Split the beginning sanity checks to a separate fold group called
  "smoketest". Also, don't unset errexit until that part is done, so
  that we will immediately fail out of the job if the smoketest fails.
  Unsetting errexit is only useful in the later regular tests that could
  be a little flaky.

Fix macvim-dev#1073

Author: ychin

.travis.yml

@@ -61,12 +61,13 @@ script:
       grep -q -- "-DDYNAMIC_RUBY_DLL=\\\\\"${vi_cv_dll_name_ruby}\\\\\"" src/auto/config.mk
     fi
   - echo -en "travis_fold:end:configure\\r\\033[0K"
+
   - echo -e "\\033[33;1mBuilding MacVim\\033[0m" && echo -en "travis_fold:start:build\\r\\033[0K"
   - make -j${NPROC}
   - echo -en "travis_fold:end:build\\r\\033[0K"
-  - set +o errexit
   - ${VIMCMD} --version
-  - echo -e "\\033[33;1mTesting MacVim\\033[0m" && echo -en "travis_fold:start:test\\r\\033[0K"
+
+  - echo -e "\\033[33;1mSmoketest\\033[0m" && echo -en "travis_fold:start:smoketest\\r\\033[0K"
   # Smoketest scripting languages
   - |
     macvim_excmd() {
@@ -84,7 +85,20 @@ script:
     if [[ -n "${HAS_GETTEXT}" ]]; then
       ${VIMCMD} -es -c 'lang es_ES' -c 'redir @a' -c 'version' -c 'put a' -c 'print' -c 'qa!' | grep Enlazado
     fi
-  # Run standard test suites
+  # Make sure there isn't any dynamic linkage to third-party dependencies in the built binary, as we should only use
+  # static linkage to avoid dependency hell. First, sanity check that we have some dylib linkage to make sure objdump is
+  # working properly, then test that all those dylib's are in /usr/lib which is bundled with macOS and not third-party.
+  - |
+    if (which objdump > /dev/null); then
+      objdump -p ${VIMCMD} | grep -q dylib &&
+      ! (objdump -p ${VIMCMD} | grep dylib | grep -v "name /usr/lib/")
+    fi
+  - echo -en "travis_fold:end:smoketest\\r\\033[0K"
+
+  # Run standard test suites.
+  # Disable errexit so flaky tests won't immediately exit to allow us to see all the errors.
+  - set +o errexit
+  - echo -e "\\033[33;1mTesting MacVim\\033[0m" && echo -en "travis_fold:start:test\\r\\033[0K"
   - make test
   - make -C runtime/doc vimtags VIMEXE=../../src/MacVim/build/Release/MacVim.app/Contents/bin/vim
   - echo -en "travis_fold:end:test\\r\\033[0K"