Sync libc-test/build.rs with libc-0.2 where possible

Author: tgross35

libc-test/build.rs

@@ -2608,6 +2608,7 @@ fn test_freebsd(target: &str) {
         match name {
             // This is introduced in FreeBSD 14.1
             "execvpe" => true,
+
             // The `uname` function in the `utsname.h` FreeBSD header is a C
             // inline function (has no symbol) that calls the `__xuname` symbol.
             // Therefore the function pointer comparison does not make sense for it.
@@ -3695,17 +3696,19 @@ fn test_linux(target: &str) {
         if musl && (ty.ends_with("64") || ty.ends_with("64_t")) {
             return true;
         }
+
         // FIXME: sparc64 CI has old headers
         if sparc64 && (ty == "uinput_ff_erase" || ty == "uinput_abs_setup") {
             return true;
         }
-        // FIXME(https://github.com/rust-lang/libc/issues/1558): passing by
-        // value corrupts the value for reasons not understood.
+
+        // FIXME(#1558): passing by value corrupts the value for reasons not understood.
         if (gnu && sparc64) && (ty == "ip_mreqn" || ty == "hwtstamp_config") {
             return true;
         }
-        // FIXME: pass by value for structs that are not an even 32/64 bits on
-        // big-endian systems corrupts the value for unknown reasons.
+
+        // FIXME(rust-lang/rust#43894): pass by value for structs that are not an even 32/64 bits
+        // on big-endian systems corrupts the value for unknown reasons.
         if (sparc64 || ppc || ppc64 || s390x)
             && (ty == "sockaddr_pkt"
                 || ty == "tpacket_auxdata"
@@ -3716,6 +3719,7 @@ fn test_linux(target: &str) {
         {
             return true;
         }
+
         // FIXME: musl doesn't compile with `struct fanout_args` for unknown reasons.
         if musl && ty == "fanout_args" {
             return true;