Externals: add hidapi

Current master (d17db57b9d4354752e0af42f5f33007a42ef2906) because
Android support was added after the current release (0.8.0-rc1).

Externals/hidapi/windows/Makefile.am

@@ -0,0 +1,16 @@
+lib_LTLIBRARIES = libhidapi.la
+libhidapi_la_SOURCES = hid.c
+libhidapi_la_LDFLAGS = $(LTLDFLAGS)
+AM_CPPFLAGS = -I$(top_srcdir)/hidapi/
+libhidapi_la_LIBADD = $(LIBS)
+
+hdrdir = $(includedir)/hidapi
+hdr_HEADERS = $(top_srcdir)/hidapi/hidapi.h
+
+EXTRA_DIST = \
+  ddk_build \
+  hidapi.vcproj \
+  hidtest.vcproj \
+  Makefile-manual \
+  Makefile.mingw \
+  hidapi.sln