The Debian packaging of pupnp-1.8 is maintained in git, using the
merging workflow described in dgit-maint-merge(7).  There isn't a
patch queue that can be represented as a quilt series.

A detailed breakdown of the changes is available from their canonical
representation - git commits in the packaging repository.  For
example, to see the changes made by the Debian maintainer in the first
upload of upstream version 1.2.3, you could use:

    % git clone https://git.dgit.debian.org/pupnp-1.8
    % cd pupnp-1.8
    % git log --oneline 1.2.3..debian/1.2.3-1 -- . ':!debian'

(If you have dgit, use `dgit clone pupnp-1.8`, rather than plain
`git clone`.)

A single combined diff, containing all the changes, follows.
Index: pupnp-1.8-1.8.4/configure.ac
===================================================================
--- pupnp-1.8-1.8.4.orig/configure.ac
+++ pupnp-1.8-1.8.4/configure.ac
@@ -573,9 +573,6 @@ freebsd*)
 		#:
 		# Use -O0 in debug so that variables do not get optimized out
 		AX_CFLAGS_GCC_OPTION([-O0, -g])
-	else
-		# add optimise for size
-		AX_CFLAGS_GCC_OPTION([-Os])
 	fi
 	;;
 esac
@@ -713,6 +710,12 @@ AC_COMPILE_IFELSE(
 			AC_MSG_ERROR([pthread_rwlock_t not available])])])
 echo "-------------------------------------------------------------------------------"
 
+AC_MSG_CHECKING([for LFS_CFLAGS])
+if test "$cross_compiling" != yes; then
+    lfs_cflags=$(getconf LFS_CFLAGS)
+fi
+AC_MSG_RESULT([$lfs_cflags])
+AC_SUBST([LFS_CFLAGS], [$lfs_cflags])
 
 AC_CONFIG_FILES([
 	Makefile
--- pupnp-1.8-1.8.4.orig/libupnp.pc.in
+++ pupnp-1.8-1.8.4/libupnp.pc.in
@@ -7,5 +7,5 @@ Name: libupnp
 Description: Linux SDK for UPnP Devices
 Version: @VERSION@
 Libs: @PTHREAD_CFLAGS@ @PTHREAD_LIBS@ -L${libdir} -lupnp -lixml
-Cflags: @PTHREAD_CFLAGS@ -I${includedir}/upnp
+Cflags: @PTHREAD_CFLAGS@ -I${includedir}/upnp @LFS_CFLAGS@
 
