Fix gcc spawn support

Don't use inode comparison to determine directory equality, and
don't try to write to /dev/null (can be removed when MG-434 is
fixed).

Change-Id: If62b5fed006b8e10aa5167d8ac45a31e30201c47
diff --git a/patches/gcc-patch.txt b/patches/gcc-patch.txt
index 1cf8639..403f226 100644
--- a/patches/gcc-patch.txt
+++ b/patches/gcc-patch.txt
@@ -257,10 +257,10 @@
 + 
 diff -rdcp --unidirectional-new-file gcc-6.2.0-fsf/gcc/config/fuchsia.h gcc-6.2.0/gcc/config/fuchsia.h
 *** gcc-6.2.0-fsf/gcc/config/fuchsia.h	1969-12-31 16:00:00.000000000 -0800
---- gcc-6.2.0/gcc/config/fuchsia.h	2016-12-09 16:41:30.153720864 -0800
+--- gcc-6.2.0/gcc/config/fuchsia.h	2016-12-20 17:04:59.055746685 -0800
 ***************
 *** 0 ****
---- 1,99 ----
+--- 1,105 ----
 + /* Base configuration file for all Fuchsia targets.
 +    Copyright (C) 2016 Free Software Foundation, Inc.
 + 
@@ -331,6 +331,12 @@
 +     }						\
 +   while (false)
 + 
++ /* /dev/null is unwritable, at the moment. Use this as a workaround.  */
++ #undef  HOST_BIT_BUCKET
++ #define HOST_BIT_BUCKET "/tmp/.null"
++ 
++ /* Inode numbers are not available to us.  */
++ #define HOST_LACKS_INODE_NUMBERS
 + 
 + /* In fact we have ftw.h, but the function itself is unimplemented.  */
 + #undef HAVE_FTW_H