package/libiio: fix python bindings without glibc utils

Libiio python bindings use ctypes and specifically the find_library()
function from there to load the libiio.so shared library. This is not
working unless glibc utils (specifically ldconfig) is installed to the
target (alternatively the target would need gcc or binutils, for objdump
or ld).

The easy fix here is to just bypass the find_library() machinery
altogether as it's not needed on a buildroot system.

Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
Tested-by: Fiona Klute <fiona.klute@gmx.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libiio/0001-bindings-python-fix-library-loading.patch

@@ -0,0 +1,41 @@
+From 4d4d17e2810f793b9f7fd8acad2a3c551dbff2b5 Mon Sep 17 00:00:00 2001
+From: Marcus Hoffmann <marcus.hoffmann@othermo.de>
+Date: Fri, 31 Mar 2023 20:13:07 +0200
+Subject: [PATCH] bindings: python: fix library loading
+
+On Linux the find_library() function requires ld, gcc, objdump
+or ldconfig on the target, which might not be present on a
+buildroot system. [1]
+We do not actually need this function at all, as we know the iio library
+will be referencable in the system under the name "libiio.so".
+So instead of kicking of this complicated cross-platform/cross-distro
+compatible machinery, we just pass in the name of the library we already
+know.
+
+[1] https://docs.python.org/3/library/ctypes.html#finding-shared-libraries
+
+Upstream: N/A, buildroot doesn't have to care about different OS's and
+distro setups, so we can just hardcode the lib name, but we cannot
+submit that upstream.
+
+Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
+---
+ bindings/python/iio.py | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/bindings/python/iio.py b/bindings/python/iio.py
+index b91260cc..bde17694 100644
+--- a/bindings/python/iio.py
++++ b/bindings/python/iio.py
+@@ -224,7 +224,7 @@ else:
+     # Non-windows, possibly Posix system
+     _iiolib = "iio"
+ 
+-_lib = _cdll(find_library(_iiolib), use_errno=True, use_last_error=True)
++_lib = _cdll("libiio.so", use_errno=True, use_last_error=True)
+ 
+ _get_backends_count = _lib.iio_get_backends_count
+ _get_backends_count.restype = c_uint
+-- 
+2.25.1
+