Fix definitions of FIONBIO/FIONCLEX/FIOCLEX constants on s390x-musl.

On musl, these constants must be ints, not ulongs.  On glibc, they are
ulong, and as such, were erroneously included as ulongs in the initial
s390x-musl definitions.

Author: kaniini

src/unix/linux_like/linux/musl/b64/s390x.rs

@@ -141,9 +141,9 @@ pub const EDEADLK: ::c_int = 35;
 pub const ENOSYS: ::c_int = 38;
 pub const ENOTCONN: ::c_int = 107;
 pub const ETIMEDOUT: ::c_int = 110;
-pub const FIOCLEX: ::c_ulong = 0x5451;
-pub const FIONCLEX: ::c_ulong = 0x5450;
-pub const FIONBIO: ::c_ulong = 0x5421;
+pub const FIOCLEX: ::c_int = 0x5451;
+pub const FIONCLEX: ::c_int = 0x5450;
+pub const FIONBIO: ::c_int = 0x5421;
 pub const O_APPEND: ::c_int = 1024;
 pub const O_CREAT: ::c_int = 64;
 pub const O_EXCL: ::c_int = 128;