riff: fix build failure from --locked

Since the addition of --locked to cargo's build command in #43233, the existing
patch causes the build to fail. Cargo add updates the lock file, solving the
issue.

srcpkgs/riff/patches/doublebuild.patch

@@ -1,14 +0,0 @@
-Slight hack to prevent a rebuild in the install phase
-
---
-
---- a/Cargo.toml
-+++ b/Cargo.toml
-@@ -20,6 +20,7 @@
- num_cpus = "1.13.0"
- threadpool = "1.8.1"
- itertools = "0.10.1"
-+syn = {version = "1.0.48", features = ["full"]}
-
- [dev-dependencies]
- pretty_assertions = "0.6.1"

srcpkgs/riff/template

@@ -1,7 +1,7 @@
 # Template file for 'riff'
 pkgname=riff
 version=2.23.2
-revision=1
+revision=2
 build_style=cargo
 short_desc="Diff filter highlighting which line parts have changed"
 maintainer="0x5c <dev@0x5c.io>"
@@ -10,6 +10,14 @@ homepage="https://github.com/walles/riff"
 distfiles="https://github.com/walles/riff/archive/refs/tags/${version}.tar.gz"
 checksum=fc39a75a6e09a3d94c6b2d8a3ad1f7aacae5a9e6da2f66f7b26dac55e82b62f3
 
+post_patch() {
+	# Needed to prevent a rebuilt in do_install()
+	# These are already transitive deps at those versions, but cargo
+	# miscalculates that a feature is dropped when installing.
+	cargo add syn@1.0.48 --features full
+	cargo add libc@0.2.140 --features extra_traits
+}
+
 post_install() {
 	vlicense LICENSE
 }