windows/uasyncio: Add support for uasyncio to windows dev variant.

ports/windows/msvc/sources.props

@@ -7,6 +7,7 @@
     <PyExtModSource Include="$(PyBaseDir)extmod\machine_pinbase.c" />
     <PyExtModSource Include="$(PyBaseDir)extmod\machine_pulse.c" />
     <PyExtModSource Include="$(PyBaseDir)extmod\machine_signal.c" />
+    <PyExtModSource Include="$(PyBaseDir)extmod\moduasyncio.c" />
     <PyExtModSource Include="$(PyBaseDir)extmod\modubinascii.c" />
     <PyExtModSource Include="$(PyBaseDir)extmod\moductypes.c" />
     <PyExtModSource Include="$(PyBaseDir)extmod\moduhashlib.c" />

ports/windows/variants/dev/manifest.py

@@ -1 +1,2 @@
 include("$(PORT_DIR)/variants/manifest.py")
+include("$(MPY_DIR)/extmod/uasyncio/manifest.py")

ports/windows/variants/dev/mpconfigvariant.h

@@ -37,3 +37,7 @@
 #define MICROPY_PY_URANDOM_EXTRA_FUNCS          (1)
 #define MICROPY_PY_BUILTINS_SLICE_INDICES       (1)
 #define MICROPY_PY_USELECT                      (1)
+
+#ifndef MICROPY_PY_UASYNCIO
+#define MICROPY_PY_UASYNCIO                     (1)
+#endif