linux-user: Rename TARGET_ERESTARTSYS to QEMU_ERESTARTSYS

This value is fully internal to qemu, and so is not a TARGET define.
We use this as an extra marker for both host and target errno.

Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/mips/cpu_loop.c

@@ -141,7 +141,7 @@ done_syscall:
                              env->active_tc.gpr[8], env->active_tc.gpr[9],
                              env->active_tc.gpr[10], env->active_tc.gpr[11]);
 # endif /* O32 */
-            if (ret == -TARGET_ERESTARTSYS) {
+            if (ret == -QEMU_ERESTARTSYS) {
                 env->active_tc.PC -= 4;
                 break;
             }