feat: Add 32-bit GameMode libraries (#416)

Some games require that GameMode be a 32-bit library. This PR adds a
build of the 32-bit versions of the GameMode libraries and binary.

You can test it by adding these launch options to a game: `gamemoderun
%command%`

snap/snapcraft.yaml

@@ -312,21 +312,42 @@ parts:
     source: https://github.com/FeralInteractive/gamemode.git
     source-tag: "1.8.2"
     plugin: meson
+    build-environment:
+      - CC: gcc -m32
+      - CXX: g++ -m32
+      - PKG_CONFIG_PATH: /usr/lib/i386-linux-gnu/pkgconfig:/usr/lib/x86_64-linux-gnu/pkgconfig:/usr/lib/pkgconfig
     organize:
       snap/steam/current/usr: usr
     meson-parameters:
       - --prefix=/usr
+      - --libdir=lib/i386-linux-gnu
     build-packages:
-      - libsystemd-dev
+      - libsystemd-dev:i386
+      - libdbus-1-dev:i386
       - pkg-config
-      - libdbus-1-dev
-    stage-packages:
-      - libinih1
-    prime:
+    stage:
       - usr/bin/gamemode*
       - usr/lib/*/libgamemode*.so.*
       - usr/lib/*/libinih.so.*
 
+  gamemode64:
+    after: [meson-deps, gamemode]
+    source: https://github.com/FeralInteractive/gamemode.git
+    source-tag: "1.8.2"
+    plugin: meson
+    organize:
+      snap/steam/current/usr: usr
+    meson-parameters:
+      - --prefix=/usr
+      - --libdir=lib/x86_64-linux-gnu
+    build-packages:
+      - libsystemd-dev
+      - libdbus-1-dev
+      - pkg-config
+    stage:
+      - usr/lib/*/libgamemode*.so.*
+      - usr/lib/*/libinih.so.*
+
   debug-tools:
     plugin: nil
     stage-packages: