Only include 'sys/user.h' for Linux. Fixes a compilation error on
FreeBSD 5.0.

diff --git a/server/context_i386.c b/server/context_i386.c
index 87d1da1..874d1dd 100644
--- a/server/context_i386.c
+++ b/server/context_i386.c
@@ -20,9 +20,6 @@
 #ifdef HAVE_SYS_PARAM_H
 # include <sys/param.h>
 #endif
-#ifdef HAVE_SYS_USER_H
-# include <sys/user.h>
-#endif
 
 #include "winbase.h"
 #include "thread.h"
@@ -58,6 +55,9 @@
 #endif
 
 #ifdef linux
+#ifdef HAVE_SYS_USER_H
+# include <sys/user.h>
+#endif
 
 /* user_regs definitions from asm/user.h */
 struct kernel_user_regs_struct