Require rust >= 1.26 and drop libc_int128 conditional

[ resolve conflicts and add test skips that seem to be needed now -
  Trevor ]

(apply <rust-lang#4060> to `main`)
(cherry picked from commit 23a0d01)

libc-test/build.rs

@@ -318,6 +318,9 @@ fn test_apple(target: &str) {
             // FIXME: Requires the macOS 14.4 SDK.
             "os_sync_wake_by_address_flags_t" | "os_sync_wait_on_address_flags_t" => true,
 
+            // FIXME: "'__uint128' undeclared" in C
+            "__uint128" => true,
+
             _ => false,
         }
     });
@@ -1804,6 +1807,10 @@ fn test_android(target: &str) {
             // These are intended to be opaque
             "posix_spawn_file_actions_t" => true,
             "posix_spawnattr_t" => true,
+
+            // FIXME: "'__uint128' undeclared" in C
+            "__uint128" => true,
+
             _ => false,
         }
     });
@@ -3659,7 +3666,7 @@ fn test_linux(target: &str) {
             "priority_t" if musl => true,
             "name_t" if musl => true,
 
-            // FIXME: Somehow fails to test after removing cfg hacks:
+            // FIXME: "'__uint128' undeclared" in C
             "__uint128" => true,
 
             t => {

src/fixed_width_ints.rs

@@ -20,7 +20,16 @@ pub type uint32_t = u32;
 pub type uint64_t = u64;
 
 cfg_if! {
-    if #[cfg(all(target_arch = "aarch64", not(any(target_os = "windows", target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))))] {
+    if #[cfg(all(
+        target_arch = "aarch64",
+        not(any(
+            target_os = "windows",
+            target_os = "macos",
+            target_os = "ios",
+            target_os = "tvos",
+            target_os = "watchos",
+        ))
+    ))] {
         // This introduces partial support for FFI with __int128 and
         // equivalent types on platforms where Rust's definition is validated
         // to match the standard C ABI of that platform.

src/unix/linux_like/android/b64/aarch64/mod.rs

@@ -76,6 +76,12 @@ s! {
         // auto-derive traits like Debug
         __reserved: [[u64; 32]; 16],
     }
+
+    pub struct user_fpsimd_struct {
+        pub vregs: [::__uint128_t; 32],
+        pub fpsr: u32,
+        pub fpcr: u32,
+    }
 }
 
 s_no_extra_traits! {
@@ -466,6 +472,3 @@ pub const PROT_MTE: ::c_int = 0x20;
 // From NDK's asm/auxvec.h
 pub const AT_SYSINFO_EHDR: ::c_ulong = 33;
 pub const AT_VECTOR_SIZE_ARCH: ::c_ulong = 2;
-
-mod int128;
-pub use self::int128::*;

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

@@ -217,6 +217,12 @@ s! {
         __reserved: [[u64; 32]; 16],
     }
 
+    pub struct user_fpsimd_struct {
+        pub vregs: [::__uint128_t; 32],
+        pub fpsr: ::c_uint,
+        pub fpcr: ::c_uint,
+    }
+
     #[repr(align(8))]
     pub struct clone_args {
         pub flags: ::c_ulonglong,
@@ -964,6 +970,3 @@ cfg_if! {
         pub use self::lp64::*;
     }
 }
-
-mod int128;
-pub use self::int128::*;

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

@@ -101,6 +101,12 @@ s! {
         pub set_tid_size: ::c_ulonglong,
         pub cgroup: ::c_ulonglong,
     }
+
+    pub struct user_fpsimd_struct {
+        pub vregs: [::__uint128_t; 32],
+        pub fpsr: u32,
+        pub fpcr: u32,
+    }
 }
 
 s_no_extra_traits! {
@@ -686,6 +692,3 @@ pub const VMIN: usize = 6;
 pub const IEXTEN: ::tcflag_t = 0x00008000;
 pub const TOSTOP: ::tcflag_t = 0x00000100;
 pub const FLUSHO: ::tcflag_t = 0x00001000;
-
-mod int128;
-pub use self::int128::*;