Auto merge of #1624 - noam93k:master, r=gnzlbg

Add dlmopen dlinfo and related consts.

I actually have no idea if the constants I copied from my computer are cross-platform.

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

 pub type pthread_t = c_ulong;
 pub type __priority_which_t = ::c_uint;
 pub type __rlimit_resource_t = ::c_uint;
+pub type Lmid_t = ::c_long;
 
 s! {
     pub struct statx {
@@ -337,6 +338,21 @@ pub const USER_PROCESS: ::c_short = 7;
 pub const DEAD_PROCESS: ::c_short = 8;
 pub const ACCOUNTING: ::c_short = 9;
 
+// dlfcn.h
+pub const LM_ID_BASE: ::c_long = 0;
+pub const LM_ID_NEWLM: ::c_long = -1;
+
+pub const RTLD_DI_LMID: ::c_int = 1;
+pub const RTLD_DI_LINKMAP: ::c_int = 2;
+pub const RTLD_DI_CONFIGADDR: ::c_int = 3;
+pub const RTLD_DI_SERINFO: ::c_int = 4;
+pub const RTLD_DI_SERINFOSIZE: ::c_int = 5;
+pub const RTLD_DI_ORIGIN: ::c_int = 6;
+pub const RTLD_DI_PROFILENAME: ::c_int = 7;
+pub const RTLD_DI_PROFILEOUT: ::c_int = 8;
+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 SOL_RXRPC: ::c_int = 272;
@@ -1024,6 +1040,20 @@ extern "C" {
     ) -> ::c_int;
 }
 
+#[link(name = "dl")]
+extern "C" {
+    pub fn dlmopen(
+        lmid: Lmid_t,
+        filename: *const ::c_char,
+        flag: ::c_int,
+    ) -> *mut ::c_void;
+    pub fn dlinfo(
+        handle: *mut ::c_void,
+        request: ::c_int,
+        info: *mut ::c_void,
+    ) -> ::c_int;
+}
+
 cfg_if! {
     if #[cfg(any(target_arch = "x86",
                  target_arch = "arm",