os/utils.c: Fix compilation of OsBlockSIGIO when SIGIO isn't defined

Fix compilation of OsBlockSIGIO with -Werror=return-type when SIGIO isn't
defined.

/jhbuild/checkout/xorg/xserver/os/utils.c: In function 'OsBlockSIGIO':
/jhbuild/checkout/xorg/xserver/os/utils.c:1248:1: error: control reaches end of non-void function [-Wreturn-type]

v2: Shuffle around to avoid writing unreachable code

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Tested-by: Yaakov Selkowitz <yselkowitz@users.sourceforge.net>
Reviewed-by: Keith Packard <keithp@keithp.com>

os/utils.c

@@ -1231,10 +1231,10 @@ OsBlockSIGIO(void)
         sigprocmask(SIG_BLOCK, &set, &PreviousSigIOMask);
         ret = sigismember(&PreviousSigIOMask, SIGIO);
         return ret;
-    } else
-        return 1;
+    }
 #endif
 #endif
+    return 1;
 }
 
 void