Don't pollute incdir with absolute directories, it's bad when
cross-compiling.
Patch configure directly since autoreconf isn't clean.

Patch status: notified upstream.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

diff -Nura lft-3.74.orig/configure lft-3.74/configure
--- lft-3.74.orig/configure	2016-05-03 14:11:30.964530888 -0300
+++ lft-3.74/configure	2016-05-03 14:12:45.038106775 -0300
@@ -5732,15 +5732,6 @@
 
 
 
-for incdir in /usr/local/include /usr/include
-do
-  if test -d $incdir/pcap
-  then
-    CFLAGS="$CFLAGS -I$incdir/pcap"
-    CPPFLAGS="$CFLAGS -I$incdir/pcap"
-  fi
-done
-
 cat >conftest.$ac_ext <<_ACEOF
 /* confdefs.h.  */
 _ACEOF