Merge branch 'fix_thread_spawn' into 'master'

Don't map thread stacks as MAP_SHARED (lol), fix i686 signal trampoline

See merge request redox-os/relibc!465

src/platform/redox/signal.rs

@@ -291,8 +291,10 @@ asmfunction!(__relibc_internal_sigentry: ["
     call {inner}
 
     add esp, 512
+    fxrstor [esp]
+
     mov eax, {SYS_SIGRETURN}
-    syscall
+    int 0x80
 "] <= [inner = sym inner_fastcall, SYS_SIGRETURN = const SYS_SIGRETURN]);
 
 #[cfg(target_arch = "aarch64")]

src/pthread/mod.rs

@@ -127,7 +127,7 @@ pub(crate) unsafe fn create(
             core::ptr::null_mut(),
             stack_size,
             sys_mman::PROT_READ | sys_mman::PROT_WRITE,
-            sys_mman::MAP_SHARED | sys_mman::MAP_ANONYMOUS,
+            sys_mman::MAP_PRIVATE | sys_mman::MAP_ANONYMOUS,
             -1,
             0,
         );