For testing we need to build some ELF files containing binman symbols. Add
these to the Makefile and check in the binaries:

   u_boot_binman_syms - normal, valid ELF file
   u_boot_binman_syms_bad - missing the __image_copy_start symbol
   u_boot_binman_syms_size - has a binman symbol with an invalid size
Signed-off-by: NSimon Glass <sjg@chromium.org>

Add a test that we can pad the BSS with zero bytes.
Signed-off-by: NSimon Glass <sjg@chromium.org>

These test programs are includedd as binary files in U-Boot to avoid
having to build them (and associated toolchain differences). Instructions
on building are in the files themselves, but it seems better to provide
a Makefile which can be manually run when desired.

Add a Makefile, separate from the normal build system, to handle this.
Signed-off-by: NSimon Glass <sjg@chromium.org>