Add mmap flag 'MAP_SYNC' to linux/mod.rs

Author: Connor Kuehl

src/unix/linux_like/linux/mod.rs

@@ -2307,6 +2307,10 @@ pub const ALG_OP_ENCRYPT: ::c_int = 1;
 // include/uapi/linux/mman.h
 pub const MAP_SHARED_VALIDATE: ::c_int = 0x3;
 
+// include/uapi/asm-generic/mman-common.h
+#[cfg(not(any(target_arch = "mips", target_arch = "mips64")))]
+pub const MAP_SYNC : ::c_int = 0x080000;
+
 // uapi/linux/vm_sockets.h
 pub const VMADDR_CID_ANY: ::c_uint = 0xFFFFFFFF;
 pub const VMADDR_CID_HYPERVISOR: ::c_uint = 0;