fix spelling in linux-user sub directory

Cc: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 78e3380..ded12ca 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -80,7 +80,7 @@
     [SIGSYS] = TARGET_SIGSYS,
     /* next signals stay the same */
     /* Nasty hack: Reverse SIGRTMIN and SIGRTMAX to avoid overlap with
-       host libpthread signals.  This assumes noone actually uses SIGRTMAX :-/
+       host libpthread signals.  This assumes no one actually uses SIGRTMAX :-/
        To fix this properly we need to do manual signal delivery multiplexed
        over a single host signal.  */
     [__SIGRTMIN] = __SIGRTMAX,