Merge patch series "some string cleanup, and a tweak of the "config" command"

Rasmus Villemoes <rv@rasmusvillemoes.dk> says:

This started by me wanting something like what patch 8 does. That
wasn't too hard, except we had no strcasestr(), and also our regex
engine (which I didn't really want to pull into the mix anyway)
doesn't have a flag that requests case-insensitive matching. So I
wanted to add strcasestr(), but then I stumbled on a bunch of stuff
that should be cleaned up in str-land.

Link: https://lore.kernel.org/r/20260708203711.849489-1-rv@rasmusvillemoes.dk

doc/usage/cmd/config.rst

@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. index::
+   single: config (command)
+
+config command
+==============
+
+Synopsis
+--------
+
+::
+
+    config [<str>]
+
+Description
+-----------
+
+The config command prints the `.config` file used when building U-Boot
+to the console. Note that the `.config` file is usually several 1000
+lines long.
+
+If the optional argument is given, only lines containing that string
+(case insensitively) are printed. That can be useful if one wants to
+check whether a specific option is enabled, or just to limit the
+output to the subsystem of interest.
+
+The `.config` file is stored inside the U-Boot binary in
+gzip-compressed format.
+
+Examples
+--------
+
+.. code-block:: bash
+
+    # Print the entire .config
+    config
+
+    # Print all lines related to pinctrl
+    config pinctrl