usrp: Corrected build fix for libusb

diff --git a/config/usrp_libusb.m4 b/config/usrp_libusb.m4
index 73872eaef0fd619e95b090f578ec5c9887fae92b..0c271e0f33e3d0600710d84cf9ec838e8bc92ed9 100644 (file)
--- a/config/usrp_libusb.m4
+++ b/config/usrp_libusb.m4
@@ -55,11 +55,11 @@ AC_DEFUN([USRP_LIBUSB], [
     ])
   fi
 
-  if x$USB_INCLUDEDIR != x; then
-    USB_INCLUDES=-I$USB_INCLUDEDIR
-  fi
-
   if test x$libusbok = xyes; then
+    if test x$USB_INCLUDEDIR != x; then
+      USB_INCLUDES="-I$USB_INCLUDEDIR"
+      AC_SUBST(USB_INCLUDES)
+    fi
     AC_SUBST(USB_LIBS)
     ifelse([$2], , :, [$2])
   else