* testsuite/include/check.h: New header file to use with
test cases.
* testsuite/lib/newlib.exp: Add testsuite/include directory
to list of header files to use.
* testsuite/newlib.wctype/twctype.c: New test case for iswctype fns.
* testsuite/newlib.wctype/wctype.exp: New file.