Auto merge of #2582 - devnexen:pidfd_syscall_flag, r=Amanieu

linux add pidfd_open syscall mode

Author: bors

libc-test/build.rs

@@ -3150,6 +3150,9 @@ fn test_linux(target: &str) {
             | "UDP_SEGMENT"
                 if uclibc => true,
 
+            // headers conflicts with linux/pidfd.h
+            "PIDFD_NONBLOCK" => true,
+
             _ => false,
         }
     });

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

@@ -597,6 +597,7 @@ pub const RTLD_DI_TLS_MODID: ::c_int = 9;
 pub const RTLD_DI_TLS_DATA: ::c_int = 10;
 
 pub const SOCK_NONBLOCK: ::c_int = O_NONBLOCK;
+pub const PIDFD_NONBLOCK: ::c_uint = O_NONBLOCK as ::c_uint;
 
 pub const SOL_RXRPC: ::c_int = 272;
 pub const SOL_PPPOL2TP: ::c_int = 273;