* ensure that the SysCall unit is also usable when FPC_USE_LIBC is defined

rtl/unix/syscall.pp

@@ -9,11 +9,22 @@ interface
 {$i syscallh.inc}
 
 implementation
+{$ifdef FPC_USE_LIBC}
+uses
+  unixtype;
+{$endif}
+
 {$ifdef FPC_HAS_SETSYSNR_INC}
 {$define FPC_COMPILING_SYSCALL_UNIT}
 {$I setsysnr.inc}
 {$endif FPC_HAS_SETSYSNR_INC}
 
+{$ifdef FPC_USE_LIBC}
+procedure seterrno(err:cint); external name 'FPC_SYS_SETERRNO';
+
+{$I syscall.inc}
+{$endif}
+
 {$ifdef FPC_HAS_SETSYSNR_INC}
 begin
   SetSyscallNumbers;