testsuite

[DJ Delorie]

The rule is, as best I can tell, this structure:

* the directory where the makefile has "make check" capability,
* subdirectory testsuite
* subdirectories package.*
* optionally more subdirectories
* files *.exp

If you changed winsup/Makefile.in to support "make check" then there
would have to be src/winsup/testsuite/*/*.exp

Note: you can have *more* subdirectories under testsuite/package.*,
but not *less*.

So, this would be feasible:

src/winsup
	testsuite
		cygwin.*
			winsup.api/winsup.exp (etc)
		w32api.*
		mingw.*

Personally, I'd prefer the testsuites under the packages, but that's
just to keep the mess localized.