* tests/test-float.c: Include fpucw.h and macros.h only after checking
the macros.
* tests/test-glob-h.c: Include macros.h only after checking the types
and macros.
* tests/test-inttypes.c: Don't include <stddef.h>.
* tests/test-math.c: Include <limits.h> and macros.h only after checking
the types and macros.
* tests/test-stddef.c: Include <limits.h> only after checking the types
and macros.
* tests/test-sys_select.c: Include signature.h only after checking the
types.
* tests/test-sys_socket.c: Include <errno.h> only after checking the
types and macros.
* tests/test-wctype-h.c: Include macros.h only after checking the types.