Remove subshell calls to "make" inside Makefile/Makefile.win

We have this pattern all over the Makefiles and it is code smell.

Example:
```
check: all python-black
@$(MAKE) eunit
@$(MAKE) javascript
@$(MAKE) mango-test
@$(MAKE) elixir
```

Figure out why this is, and fix it.

Read the Makefile and Makefile.win, starting with the check target and its repeated $(MAKE) calls. Determine why these subshell invocations are used, then verify that the affected checks still run correctly without the code-smell pattern.

Written by the indexing model from the issue text.