Add valgrind headers to U-Boot

Valgrind uses magic code sequences to define an ABI that the client may use
to request behavior from the host. In particular, this may be used to
inform valgrind about custom allocators, such as the one used in U-Boot.

This adds headers defining these sequences to U-Boot. It also adds a config
option to disable emission of these sequences entirely, in the (likely)
event that the user does not wish to use valgrind. Note that this option is
called NVALGRIND upstream, but was renamed (and inverted) to
CONFIG_VALGRIND. Aside from this and the conversion of a few instances of
VALGRIND_DO_CLIENT_REQUEST_EXPR to STMT, these headers are unmodified.

These headers were copied from valgrind 3.16.1-4 as distributed in Arch
Linux. They are licensed with the bzip2 1.16 license. This appears to be a
BSD license with some clauses from Zlib.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/Licenses/README b/Licenses/README
index c23ad21..d09f0fe 100644
--- a/Licenses/README
+++ b/Licenses/README
@@ -139,6 +139,7 @@
 
 Full name					SPDX Identifier	OSI Approved	File name		URI
 =======================================================================================================================================
+bzip2 and libbzip2 License v1.0.6		bzip2-1.0.6			bzip2-1.0.6.txt		https://spdx.org/licenses/bzip2-1.0.6.html
 GNU General Public License v2.0 only		GPL-2.0		Y		gpl-2.0.txt		http://www.gnu.org/licenses/gpl-2.0.txt
 GNU General Public License v2.0 or later	GPL-2.0+	Y		gpl-2.0.txt		http://www.gnu.org/licenses/gpl-2.0.txt
 GNU Library General Public License v2 or later	LGPL-2.0+	Y		lgpl-2.0.txt		http://www.gnu.org/licenses/old-licenses/lgpl-2.0.txt
diff --git a/Licenses/bzip2-1.0.6.txt b/Licenses/bzip2-1.0.6.txt
new file mode 100644
index 0000000..2adb26c
--- /dev/null
+++ b/Licenses/bzip2-1.0.6.txt
@@ -0,0 +1,30 @@
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. The origin of this software must not be misrepresented; you must 
+   not claim that you wrote the original software.  If you use this 
+   software in a product, an acknowledgment in the product 
+   documentation would be appreciated but is not required.
+
+3. Altered source versions must be plainly marked as such, and must
+   not be misrepresented as being the original software.
+
+4. The name of the author may not be used to endorse or promote 
+   products derived from this software without specific prior written 
+   permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
+OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.