features: Fix test TestHaveProgramType/Extension in kernel >=v6.8

In kernel v6.8, logic was added that restricts valid func info BTF for
programs that can be replaced with an BPF_PROG_TYPE_EXT program.
Before this change the parameters of the extension program had to be
the same as the original program.

Commit torvalds/linux@5eccd2db42d77e357 made
it so the verifier asserts that the BTF func info of "main" programs
must have exactly 1 parameter of a pointer type to the context struct,
even if the code doesn't use the context like in our case.

Signed-off-by: Dylan Reimerink <dylan.reimerink@isovalent.com>

features/prog.go

@@ -125,6 +125,9 @@ var haveProgramTypeMatrix = internal.FeatureMatrix[ebpf.ProgramType]{
 				Name: "a",
 				Type: &btf.FuncProto{
 					Return: &btf.Int{},
+					Params: []btf.FuncParam{
+						{Name: "ctx", Type: &btf.Pointer{Target: &btf.Struct{Name: "xdp_md"}}},
+					},
 				},
 				Linkage: btf.GlobalFunc,
 			}