Move "cord" library tests to "cord/tests" folder.

Move "cord" library tests to "cord/tests" folder.

* cord/cordtest.c, cord/de.c, cord/de_win.c, cord/de_cmds.h,
cord/de_win.h: Move to cord/tests folder.
* cord/de_win.RC: Move ad rename to cord/tests/de_win.rc.
* .gitignore: Add cord/tests/de_win.res file.
* BCC_MAKEFILE (cord/de.obj, cord/de_win.obj, cord/de_win.res):
Rename (targets and source moved to cord/tests).
* NT_MAKEFILE (cord/de.obj, cord/de_win.obj): Likewise.
* CMakeLists.txt (cord): Rename cord/de.c, cord/de_win.c (source moved
to cord/tests).
* EMX_MAKEFILE (cord/cordtest.exe, cord/de.exe): Rename
cord/cordtest.c, cord/de.c to cord/tests (source moved to cord/tests).
* Makefile.direct, Makefile.dj (cord/cordtest, cord/de): Likewise.
* OS2_MAKEFILE (cord/cordtest.exe): Likewise.
* SMakefile.amiga (cord/cordtest.o): Likewise.
* Makefile.direct, Makefile.dj (CORD_SRCS): Rename cord/cordtest.c,
cord/de.c, cord/de_cmds.h, cord/de_win.c, cord/de_win.h,
cord/de_win.rc (moved to cord/tests).
* NT_MAKEFILE, NT_STATIC_THREADS_MAKEFILE,
NT_X64_STATIC_THREADS_MAKEFILE, NT_X64_THREADS_MAKEFILE
(cord/de_win.res, cord/de.exe): Move cord/de.obj, cord/de_win.obj to
cord/tests.
* cord/cord.am (EXTRA_DIST): Move cordtest.c, de.c, de_cmds.h,
de_win.h, de_win.c, de_win.rc to cord/tests.
* doc/README.cords: Update (regarding de.c file move).
* gc.mak (SOURCE): Move de_win.c, de.c, de_win.rc to cord/tests.