always fetch bpftool from remote

Signed-off-by: ruki <waruqi@gmail.com>

Author: waruqi

.github/workflows/build-android.yml

@@ -28,4 +28,4 @@ jobs:
           && sudo apt-get -y clean
     - name: Build xmake android examples/c
       run: |
-        cd examples/c && xmake f -p android -a ${{ matrix.arch }} --require-bpftool=y -y && xmake -y
+        cd examples/c && xmake f -p android -a ${{ matrix.arch }} -y && xmake -y

examples/c/xmake.lua

@@ -9,7 +9,7 @@ if xmake.version():satisfies(">=2.5.7 <=2.5.9") then
 end
 
 option("system-libbpf",      {showmenu = true, default = false, description = "Use system-installed libbpf"})
-option("require-bpftool",    {showmenu = true, default = false, description = "Require bpftool package"})
+option("require-bpftool",    {showmenu = true, default = true, description = "Require bpftool package"})
 
 add_requires("elfutils", "zlib")
 if is_plat("android") then