Provides some of the missing POSIX file syscalls

src/trusted/desc/nacl_desc_base.h

Index: src/trusted/desc/nacl_desc_base.h
diff --git a/src/trusted/desc/nacl_desc_base.h b/src/trusted/desc/nacl_desc_base.h
index 962c99119a2ab59fece8eac275ab5b67972231ea..9520a48dbc45e2a3db82d49db6a4b52d66b03919 100644
--- a/src/trusted/desc/nacl_desc_base.h
+++ b/src/trusted/desc/nacl_desc_base.h
@@ -229,6 +229,18 @@ struct NaClDescVtbl {
   int (*Fstat)(struct NaClDesc      *vself,
                struct nacl_abi_stat *statbuf);
 
+  int (*Fchdir)(struct NaClDesc *vself) NACL_WUR;
+
+  int (*Fchmod)(struct NaClDesc *vself,
+                int             mode) NACL_WUR;
+
+  int (*Fsync)(struct NaClDesc *vself) NACL_WUR;
+
+  int (*Fdatasync)(struct NaClDesc *vself) NACL_WUR;
+
+  int (*Ftruncate)(struct NaClDesc  *vself,
+                   nacl_abi_off_t   length) NACL_WUR;
+
   /*
    * Directory access support.  Directories require support for getdents.
    */
@@ -604,6 +616,18 @@ int NaClDescIoctlNotImplemented(struct NaClDesc *vself,
 int NaClDescFstatNotImplemented(struct NaClDesc       *vself,
                                 struct nacl_abi_stat  *statbuf);
 
+int NaClDescFchdirNotImplemented(struct NaClDesc *vself);
+
+int NaClDescFchmodNotImplemented(struct NaClDesc *vself,
+                                 int             mode);
+
+int NaClDescFsyncNotImplemented(struct NaClDesc *vself);
+
+int NaClDescFdatasyncNotImplemented(struct NaClDesc *vself);
+
+int NaClDescFtruncateNotImplemented(struct NaClDesc  *vself,
+                                    nacl_abi_off_t   length);
+
 ssize_t NaClDescGetdentsNotImplemented(struct NaClDesc  *vself,
                                        void             *dirp,
                                        size_t           count);