Rename COPYRIGHT to COPYING

The standard name people have adopted is "COPYING" rather than
"COPYRIGHT".  Use that as a lot of license scanning tools look for it.

* COPYRIGHT: Rename to ...
* COPYING: ... this.
* Makefile.am (EXTRA_DIST): Rename COPYRIGHT to COPYING.
* README: Likewise.
* strace.spec (%files): Likewise.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/strace.spec b/strace.spec
index da596ad..7af635b 100644
--- a/strace.spec
+++ b/strace.spec
@@ -74,7 +74,7 @@
 
 %files
 %defattr(-,root,root)
-%doc CREDITS ChangeLog ChangeLog-CVS COPYRIGHT NEWS README
+%doc CREDITS ChangeLog ChangeLog-CVS COPYING NEWS README
 %{_bindir}/strace
 %{_bindir}/strace-log-merge
 %{_mandir}/man1/*