vboot2: Add host library functions to read/write files and objects

And unit tests for them.

Move roundup32() into hostlib.

Fix WriteFile() returning success even if it failed to write to the file.

BUG=chromium:423882
BRANCH=none
TEST=VBOOT2=1 make runtests

Change-Id: I8a115335c088dc5c66c88423d1ccbda7eaca1996
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/230844

host/lib/host_misc.c

@@ -108,6 +108,7 @@ int WriteFile(const char* filename, const void *data, uint64_t size) {
     VBDEBUG(("Unable to write to file %s\n", filename));
     fclose(f);
     unlink(filename);  /* Delete any partial file */
+    return 1;
   }
 
   fclose(f);