sdl_mixer: try to open from common path

Copy sounfont to known path for macOS and Windows CI builds (in Linux,
this is already handled with a environment var SDL_SOUNDFONTS). And also
use that location if there is any soundfont.

.github/scripts/Linux/prepare.sh

@@ -51,8 +51,9 @@ sudo apt install libva-dev libdrm-dev libx11-dev libx11-xcb-dev libxcb-present-d
 
 sudo apt install qtbase5-dev
 
-sf=TimGM6mb_but_fixed__piano_.sf2 # https://musical-artifacts.com/artifacts/2642
-curl http://frakira.fi.muni.cz/~xpulec/$sf -o "$HOME/$sf"
+. "$GITHUB_WORKSPACE/.github/scripts/defs.sh"
+sf=$(basename "$DEFAULT_SF_URL")
+curl -L "$DEFAULT_SF_URL" -o "$HOME/$sf"
 printf '%b' "SDL_SOUNDFONTS=$HOME/$sf\n" >> "$GITHUB_ENV"
 
 # Install cross-platform deps

.github/scripts/Windows/prepare_msys.sh

@@ -100,6 +100,13 @@ build_cineform() {
         )
 }
 
+install_soundfont() {
+        . "$GITHUB_WORKSPACE/.github/scripts/defs.sh"
+        sf_dir="$GITHUB_WORKSPACE/data/Windows/share/soundfonts"
+        mkdir -p "$sf_dir"
+        curl -L "$DEFAULT_SF_URL" -o "$sf_dir/default.sf2"
+}
+
 # Install cross-platform deps
 "$GITHUB_WORKSPACE/.github/scripts/install-common-deps.sh"
 
@@ -111,4 +118,5 @@ build_cineform() {
 
 build_cineform
 install_aja
+install_soundfont
 

.github/scripts/defs.sh

@@ -0,0 +1 @@
+DEFAULT_SF_URL=http://frakira.fi.muni.cz/~xpulec/TimGM6mb_but_fixed__piano_.sf2 # https://musical-artifacts.com/artifacts/2642

.github/scripts/macOS/prepare.sh

@@ -103,6 +103,13 @@ install_live555() {
         cd ..
 }
 
+install_soundfont() {
+        . "$GITHUB_WORKSPACE/.github/scripts/defs.sh"
+        sf_dir="$GITHUB_WORKSPACE/data/MacOS-bundle-template/Contents/share/soundfonts"
+        mkdir -p "$sf_dir"
+        curl -L "$DEFAULT_SF_URL" -o "$sf_dir/default.sf2"
+}
+
 install_syphon() {
         wget --no-verbose https://github.com/Syphon/Syphon-Framework/releases/download/5/Syphon.SDK.5.zip
         unzip Syphon.SDK.5.zip
@@ -117,6 +124,7 @@ install_deltacast
 install_glfw
 install_live555
 install_ndi
+install_soundfont
 install_syphon
 install_ximea