[travis] Find llvm-config using find

In homebrew llvm has changed and that is why FindLibClang.cmake cannot find
llvm-config.
  llvm-7.0.0.high_sierra.bottle.1.tar.gz --> llvm-7.0.0_1.high_sierra.bottle.tar.gz

I'm not quite sure right now if that is just in travis that case or in
general. If in general than we would need to adopt FindLibClang.cmake

Nose version also contains now "_1" at the end of the version string

scripts/travis.sh

@@ -74,9 +74,10 @@ function osx()
 
     ## Step -- Build
     mkdir -p ~/.local/bin
-    ln -s /usr/local/Cellar/numpy/1.15.4/libexec/nose/bin/nosetests-3.7 \
+    ln -s /usr/local/Cellar/numpy/*/libexec/nose/bin/nosetests-3.7 \
        ~/.local/bin/nosetests
     export PYTHONPATH=/usr/local/lib/python3.7/site-packages
+    export LIBCLANG_LLVM_CONFIG_EXECUTABLE=$(find /usr/local/Cellar/llvm/*/bin -name llvm-config 2>/dev/null)
     # Help cmake to find openssl includes/library
     add_cmake_params "-DOPENSSL_ROOT_DIR=/usr/local/opt/openssl"