emscripten: install emcmake binary

Closes #30122.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
emscripten: update 1.16.0 bottle.
pyenv-virtualenv v20140614

Changes:

* Add `pyenv virtualenv-init` to enable auto-activation feature
* Create symlinks for executables with version suffix
pyenv-virtualenv: add 20140614 bottle.