libpfring: update to 7.6.0

Fixes compilation with kernel 5.4.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

libs/libpfring/patches/0001-fix-cross-compiling.patch

@@ -1,6 +1,6 @@
 --- a/userland/configure
 +++ b/userland/configure
-@@ -3718,12 +3718,6 @@ fi
+@@ -3861,12 +3861,6 @@ fi
  if test "$IS_FREEBSD" != "1" && test "$cross_compiling" != "yes" ; then
    { $as_echo "$as_me:${as_lineno-$LINENO}: checking if r/w locks are supported" >&5
  $as_echo_n "checking if r/w locks are supported... " >&6; }
@@ -13,7 +13,7 @@
    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
  /* end confdefs.h.  */
  
-@@ -3736,7 +3730,7 @@ else
+@@ -3879,7 +3873,7 @@ else
  
  
  _ACEOF
@@ -22,7 +22,7 @@
     { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
  $as_echo "yes" >&6; }
  cat >>confdefs.h <<_ACEOF
-@@ -3750,7 +3744,6 @@ $as_echo "no" >&6; }
+@@ -3893,7 +3887,6 @@ $as_echo "no" >&6; }
  fi
  rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
    conftest.$ac_objext conftest.beam conftest.$ac_ext