build-system: add libmtp for our Windows builds

This uses latest master (as that's the only one that has the explicit
Descent Mk2i support in it).

Right now, unfortunately the MXE build fails.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

.github/workflows/scripts/windows-container-prep.sh

@@ -5,3 +5,4 @@
 echo "downloading sources for fresh build"
 bash subsurface/scripts/get-dep-lib.sh single . libzip
 bash subsurface/scripts/get-dep-lib.sh single . googlemaps
+bash subsurface/scripts/get-dep-lib.sh single . libmtp

packaging/windows/mxe-based-build.sh

@@ -153,6 +153,28 @@ if [ ! -f libdivecomputer/configure ] ; then
 	autoreconf --install
 fi
 
+# build libmtp as that isn't available via MXE
+cd "$BUILDDIR"
+if [[ ! -d libmtp || -f build.libmtp ]] ; then
+	rm -f build.libmtp
+	cd "$BASEDIR/libmtp"
+	export NOCONFIGURE=1
+	# crudely disable the interactive part of autogen.sh
+	sed --in-place=.bak 's/read IN/IN="N"/;s/echo "Auto/#echo "Auto/' autogen.sh
+	bash autogen.sh
+	mv autogen.sh.bak autogen.sh
+	cd "$BUILDDIR"
+	mkdir -p libmtp
+	cd libmtp
+	"$BASEDIR"/libmtp/configure \
+		CC="$MXEBUILDTYPE"-gcc \
+		--host="$MXEBUILDTYPE" \
+		--enable-shared \
+		--prefix="$BASEDIR"/"$MXEDIR"/usr/"$MXEBUILDTYPE"
+	make $JOBS
+	make install
+fi
+
 cd "$BUILDDIR"
 CURRENT_SHA=$(cd "$BASEDIR"/subsurface/libdivecomputer ; git describe)
 PREVIOUS_SHA=$(cat "libdivecomputer.SHA" 2>/dev/null || echo)

scripts/get-dep-lib.sh

@@ -17,6 +17,7 @@ CURRENT_KIRIGAMI="v5.62.0"
 CURRENT_BREEZE_ICONS="4daac191fb33c8c03bba8356db9767816cb8ee02"
 CURRENT_MDBTOOLS="master"
 CURRENT_QT_ANDROID_CMAKE="master"
+CURRENT_LIBMTP="master"
 
 # Checkout library from git
 # Ensure specified version is checked out,
@@ -155,6 +156,9 @@ for package in "${PACKAGES[@]}" ; do
 		libusb)
 			git_checkout_library libusb $CURRENT_LIBUSB https://github.com/libusb/libusb.git
 			;;
+		libmtp)
+			git_checkout_library libmtp $CURRENT_LIBMTP https://github.com/libmtp/libmtp.git
+			;;
 		libxml2)
 			git_checkout_library libxml2 $CURRENT_LIBXML2 https://github.com/GNOME/libxml2.git
 			;;