capnproto: regenerate patch with more clear commit message

Explain what changed, and ensure no one mistakes this for the original
upsteam commit (while giving due attribution).

pkgs/development/libraries/capnproto/musl-no-fibers.patch

@@ -1,8 +1,16 @@
-From 85b4e6074882d62593ae90d6683e24efccb045f0 Mon Sep 17 00:00:00 2001
+From 3d983eff304c28574c330a52d70a60145c9e157e Mon Sep 17 00:00:00 2001
 From: Jonas Vautherin <jonas.vautherin@gmail.com>
 Date: Fri, 14 Jan 2022 00:14:26 +0100
 Subject: [PATCH] Add support for musl
 
+---
+Based on upstream 77ac9154440bcc216fda1092fd5bb51da62ae09c,
+modified slightly by dtzWill to apply to v0.9.1.
+
+(drop whitespace change to a cmake "if (WITH_OPENSSL)",
+leave the other instance of that change since it applies)
+---
+
 Co-authored-by: Guillaume Papin <guillaume.papin@epitech.eu>
 (cherry picked from commit 77ac9154440bcc216fda1092fd5bb51da62ae09c)
 ---