xdp-tools: fix BPFTOOL detection

Fix sh syntax error in configure script.

Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>

package/network/utils/xdp-tools/Makefile

@@ -1,7 +1,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=xdp-tools
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 PKG_VERSION:=1.6.3
 PKG_HASH:=78da363ff7dcf1a586f47800f16d644022bd33f3844864061a44616fce854fd8
 

package/network/utils/xdp-tools/patches/0100-fix-configure-syntax.patch

@@ -0,0 +1,16 @@
+--- a/configure
++++ b/configure
+@@ -109,11 +109,11 @@ check_toolchain()
+         exit 1
+     fi
+ 
+-    if ! command -v $BPFTOOL &>/dev/null; then
++    if ! command -v $BPFTOOL >/dev/null 2>&1; then
+         BPFTOOL=$(whereis -b bpftool | awk '{print $2}')
+     fi
+ 
+-    if command -v $BPFTOOL &>/dev/null && $BPFTOOL gen help 2>&1 | grep 'gen skeleton.*name' > /dev/null; then
++    if command -v $BPFTOOL >/dev/null 2>&1 && $BPFTOOL gen help 2>&1 | grep 'gen skeleton.*name' > /dev/null; then
+         bpftool_version=$($BPFTOOL version | head -n 1)
+         echo "using $bpftool_version"
+     else