Merge branch 'bugfix/osx_menuconfig_build' into 'master'

Allow OS X to build without libintl

https://github.com/espressif/esp-idf/pull/42

I have tested this with the following configurations:
- OS X with Xcode command line tools, no macports, no homebrew
- OS X with Xcode command line tools and homebrew
- OS X with Xcode IDE and macports

All three work with this change, without it the first two had issues.

See merge request !172