wasapi: add PKEY_Device_FriendlyName on mingw-w64

Hopefully we can get this function merged for mingw-w64 4.1.  As for the
4.0 release, adding a new header is a big change, it'll have to wait for
the next version.

plugins/win-wasapi/enum-wasapi.hpp

@@ -5,8 +5,24 @@
 #include <mmdeviceapi.h>
 #include <audioclient.h>
 #include <propsys.h>
+
+#ifdef __MINGW32__
+
+#ifdef DEFINE_PROPERTYKEY
+#undef DEFINE_PROPERTYKEY
+#endif
+#define DEFINE_PROPERTYKEY(id, a, b, c, d, e, f, g, h, i, j, k, l) \
+	const PROPERTYKEY id = { { a,b,c, { d,e,f,g,h,i,j,k, } }, l };
+DEFINE_PROPERTYKEY(PKEY_Device_FriendlyName, \
+	0xa45c254e, 0xdf1c, 0x4efd, 0x80, \
+	0x20, 0x67, 0xd1, 0x46, 0xa8, 0x50, 0xe0, 14);
+
+#else
+
 #include <functiondiscoverykeys_devpkey.h>
 
+#endif
+
 #include <vector>
 #include <string>