os/xsha1.c: Add license and copyright attribution.

I'm interested in copying this code to the mesa project, but before
doing that it seems prudent to have the license and copyright
attributions in place before copying that. To get this list of names I
went through:

	git log -- os/xsha1.c
and:
	git log -- render/glyph.c

Signed-off-by: Keith Packard <keithp@keithp.com>

os/xsha1.c

@@ -1,3 +1,28 @@
+/* Copyright © 2007 Carl Worth
+ * Copyright © 2009 Jeremy Huddleston, Julien Cristau, and Matthieu Herrb
+ * Copyright © 2009-2010 Mikhail Gusarov
+ * Copyright © 2012 Yaakov Selkowitz and Keith Packard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
 #ifdef HAVE_DIX_CONFIG_H
 #include <dix-config.h>
 #endif