Use libusb from a tarball

Now that Wasm support is included in release tarballs, we don't need to include libusb as a submodule anymore.

.gitignore

@@ -2,5 +2,4 @@
 node_modules
 /deps/*
 !/deps/libgphoto2
-!/deps/libusb
 /src/api.o

.gitmodules

@@ -2,6 +2,3 @@
 	path = deps/libgphoto2
 	url = https://github.com/RReverser/libgphoto2
 	branch = em
-[submodule "libusb"]
-	path = deps/libusb
-	url = https://github.com/libusb/libusb

Makefile

@@ -49,15 +49,19 @@ $(SYSROOT)/lib/libltdl.la: deps/libtool/Makefile | $(SYSROOT)
 
 ## libusb
 
-deps/libusb/Makefile: CONFIGURE_ARGS = --host=wasm32
+deps/libusb/configure:
+	mkdir -p deps/libusb
+	curl -L https://github.com/libusb/libusb/releases/download/v1.0.27/libusb-1.0.27.tar.bz2 | tar jx --strip 1 -C deps/libusb
+
+deps/libusb/Makefile: CONFIGURE_ARGS = --host=wasm32-emscripten
 
 $(SYSROOT)/lib/libusb-1.0.la: deps/libusb/Makefile
 	$(MAKE) -C deps/libusb install
 
 ## libgphoto2
 
 deps/libgphoto2/Makefile: | $(SYSROOT)/lib/libusb-1.0.la
-deps/libgphoto2/Makefile: CONFIGURE_ARGS = --host=wasm32 \
+deps/libgphoto2/Makefile: CONFIGURE_ARGS = --host=wasm32-emscripten \
 	--without-libxml-2.0 --disable-nls --disable-ptpip --disable-disk \
 	--with-camlibs=ptp2