Bugfix: Adjust USB_* variables to new LIBUSB_* names

configure.ac

@@ -198,8 +198,8 @@ PKG_CHECK_MODULES([LIBUSB], [libusb-1.0],[
 				AC_MSG_CHECKING([whether libusb_init is declared in subdirectory])
 				libusb_include_path=`echo '#include <libusb-1.0/libusb.h>' | cpp -M 2>/dev/null | sed 's/^[^[:space:]]\+[[:space:]]\+\([^[:space:]]\+\)\/.*$/\1/;t;d'`
 				if test "x$libusb_include_path" != "x"; then
-					USB_LIBS="-l$usb_lib"
-					USB_CFLAGS="-I$libusb_include_path"
+					LIBUSB_LIBS="-l$usb_lib"
+					LIBUSB_CFLAGS="-I$libusb_include_path"
 					AC_MSG_RESULT([yes])
 				else
 					libusb=no