Add struct ip_mreqn to more Linux targets

Support was previously added to gnu x86_64 and all musl targets but
others were not included because of a roundtrip issue [1].

This commit adds support for the ip_mreqn struct on all Linux GNU
targets which did not have the roundtrip issue.

[1]: #1558

Signed-off-by: Bartel Sielski <bartel.sielski@gmail.com>

src/unix/linux_like/linux/gnu/b32/mod.rs

@@ -115,6 +115,12 @@ s! {
         pub mem_unit: ::c_uint,
         pub _f: [::c_char; 8],
     }
+
+    pub struct ip_mreqn {
+        pub imr_multiaddr: ::in_addr,
+        pub imr_address: ::in_addr,
+        pub imr_ifindex: ::c_int,
+    }
 }
 
 pub const O_NOATIME: ::c_int = 0o1000000;

src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs

@@ -203,6 +203,12 @@ s! {
         pub ss_flags: ::c_int,
         pub ss_size: ::size_t
     }
+
+    pub struct ip_mreqn {
+        pub imr_multiaddr: ::in_addr,
+        pub imr_address: ::in_addr,
+        pub imr_ifindex: ::c_int,
+    }
 }
 
 pub const VEOF: usize = 4;

src/unix/linux_like/linux/gnu/b64/powerpc64/mod.rs

@@ -190,6 +190,12 @@ s! {
         pub ss_flags: ::c_int,
         pub ss_size: ::size_t
     }
+
+    pub struct ip_mreqn {
+        pub imr_multiaddr: ::in_addr,
+        pub imr_address: ::in_addr,
+        pub imr_ifindex: ::c_int,
+    }
 }
 
 pub const POSIX_FADV_DONTNEED: ::c_int = 4;

src/unix/linux_like/linux/gnu/b64/riscv64/mod.rs

@@ -191,6 +191,12 @@ s! {
         pub l_len: ::off64_t,
         pub l_pid: ::pid_t,
     }
+
+    pub struct ip_mreqn {
+        pub imr_multiaddr: ::in_addr,
+        pub imr_address: ::in_addr,
+        pub imr_ifindex: ::c_int,
+    }
 }
 
 pub const POSIX_FADV_DONTNEED: ::c_int = 4;