Modularise fluxsink and usb.

lib/usb/build.py

@@ -1,4 +1,19 @@
 from build.protobuf import proto, protocc
+from build.c import cxxlibrary
 
 proto(name="proto", srcs=["./usb.proto"], deps=["lib+common_proto"])
 protocc(name="proto_lib", srcs=[".+proto"], deps=["lib+common_proto_lib"])
+
+cxxlibrary(
+    name="usb",
+    srcs=[
+        "./applesauceusb.cc",
+        "./fluxengineusb.cc",
+        "./greaseweazleusb.cc",
+        "./serial.cc",
+        "./usb.cc",
+        "./usbfinder.cc",
+    ],
+    hdrs={"lib/usb/usb.h": "./usb.h", "lib/usb/usbfinder.h": "./usbfinder.h"},
+    deps=["lib/core", "lib/config", "lib/external", "dep/libusbp", "+protocol"],
+)