[OB] Fix linux-low.c build error

[Hui Zhu <teawater@gmail.com>]

Got:
gcc -c  -g -O2    -I. -I../../../src/gdb/gdbserver
-I../../../src/gdb/gdbserver/../common
-I../../../src/gdb/gdbserver/../regformats
-I../../../src/gdb/gdbserver/../../include -Wall
-Wdeclaration-after-statement -Wpointer-arith -Wformat-nonliteral
-Wno-char-subscripts -Werror ../../../src/gdb/gdbserver/linux-low.c
-DUSE_THREAD_DB
cc1: warnings being treated as errors
../../../src/gdb/gdbserver/linux-low.c: In function ‘linux_create_inferior’:
../../../src/gdb/gdbserver/linux-low.c:580:10: error: ignoring return
value of ‘write’, declared with attribute warn_unused_result

2011-12-18  Hui Zhu  <teawater@gmail.com>

	* linux-low.c (linux_create_inferior): Save return value to ret.
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/linux-low.c,v
retrieving revision 1.185
retrieving revision 1.186
diff -u -r1.185 -r1.186
--- src/gdb/gdbserver/linux-low.c	2011/12/16 19:06:37	1.185
+++ src/gdb/gdbserver/linux-low.c	2011/12/18 15:49:04	1.186
@@ -574,11 +574,12 @@
 	 Also, redirect stdin to /dev/null.  */
       if (remote_connection_is_stdio ())
 	{
+	  int ret;
 	  close (0);
 	  open ("/dev/null", O_RDONLY);
 	  dup2 (2, 1);
-	  write (2, "stdin/stdout redirected\n",
-		 sizeof ("stdin/stdout redirected\n") - 1);
+	  ret = write (2, "stdin/stdout redirected\n",
+		       sizeof ("stdin/stdout redirected\n") - 1);
 	}

       execv (program, allargs);