[niepce] cxx: build cxx with C++17 feature

[Hubert Figuière <hub src gnome org>]

commit a575f85c879898624c0b8f59fe7ae55ea56bfb40
Author: Hubert Figuière <hub figuiere net>
Date:   Sat Oct 15 22:25:09 2022 -0400

    cxx: build cxx with C++17 feature

 crates/npc-engine/Cargo.toml | 2 +-
 crates/npc-fwk/Cargo.toml    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/crates/npc-engine/Cargo.toml b/crates/npc-engine/Cargo.toml
index 2d85fae4..fa5628e0 100644
--- a/crates/npc-engine/Cargo.toml
+++ b/crates/npc-engine/Cargo.toml
@@ -10,7 +10,7 @@ build = "build.rs"
 [dependencies]
 async-channel = "1.6.1"
 chrono = "0.4.0"
-cxx = "1.0"
+cxx = { version = "1.0", features = [ "c++17" ] }
 exempi = { version = "2.6.0", git = "https://github.com/hfiguiere/exempi-rs.git";, rev="99e8ba5" }
 gdk-pixbuf-sys = "*"
 gdk-pixbuf = "*"
diff --git a/crates/npc-fwk/Cargo.toml b/crates/npc-fwk/Cargo.toml
index 1a979dcf..4766c377 100644
--- a/crates/npc-fwk/Cargo.toml
+++ b/crates/npc-fwk/Cargo.toml
@@ -11,7 +11,7 @@ build = "build.rs"
 async-channel = "1.6.1"
 cairo-rs = "*"
 chrono = "0.4.0"
-cxx = "1.0"
+cxx = { version = "1.0", features = [ "c++17" ] }
 exempi = { version = "2.6.0", git = "https://github.com/hfiguiere/exempi-rs.git";, rev="99e8ba5" }
 gio-sys = "*"
 gio = "^0.15.7"