Bring back webkit2gtk update for RPiOS Buster

[peat-psuwit]

At the moment, RPiOS Bullseye's webkit2gtk is at version 2.38.5-1~deb11u1+rpi1. However, Debian's webkit2gtk is now at version 2.40.5-1~deb11u1. It would be nice if Raspberry Pi OS Bullseye can have a more-recent version of webkit2gtk, complete with security updates.

Presumably the build in Raspberry Pi OS is not being updated anymore because it fails to patch debian/rules. In that case, I can confirm that the following patch against Debian version allows webkit2gtk to builds on RPiOS, and runs on Raspberry Pi 1 model B:

diff --git a/debian/rules b/debian/rules
index 44076e93b9..d031c484b7 100755
--- a/debian/rules
+++ b/debian/rules
@@ -66,6 +66,16 @@ ifneq (,$(filter $(DEB_HOST_ARCH),armel mipsel m68k powerpc sh4))
        EXTRA_CMAKE_ARGUMENTS += -DENABLE_WEBGL=OFF
 endif

+# Disable JIT & WebGL for Raspbian armhf to remain compatible with armv6l.
+ifeq ($(shell dpkg-vendor --derives-from Raspbian && echo yes),yes)
+       ifneq (,$(filter $(DEB_HOST_ARCH),armhf))
+               EXTRA_CMAKE_ARGUMENTS += \
+                       -DENABLE_JIT=OFF \
+                       -DENABLE_C_LOOP=ON \
+                       -DENABLE_WEBGL=OFF
+       endif
+endif
+
 # libgbm-dev is not available in the Hurd (#1033999)
 ifneq (,$(filter $(DEB_HOST_ARCH),hurd-i386))
        EXTRA_CMAKE_ARGUMENTS += -DUSE_GBM=OFF

Webkit2gtk is useful for a couple of reasons:

• It's the last browser engine that still runs on ARMv6 i.e. Raspberry Pi 1 family & Raspberry Pi 0. Yes, it's very slow. But in some cases it might be enough (e.g. displaying static announcement).
• Being minimally patched, it has a potential to have the updates, including security updates, flowed from Debian faster.