[coreboot] problem with: vendorcode/amd/agesa/fam15: Build as a static library

[Scott Duplichan]

While trying to get abuild working from Windows I found a coreboot
makefile problem. File src/vendorcode/amd/agesa/f15/Makefile.inc is
be processed twice. While this doesn't break a Linux build, it does
break the Windows build. The Windows problem is because the ar
command line contains each object file twice, and the Windows 32KB
command line length is exceeded.

As a temporary work around, I bracket the contents if Makefile.inc with:

ifeq ($(F15_MAKE_INCLUDED),)
    export F15_MAKE_INCLUDED=y
        ...
    endif

What is the correct solution?

Thanks,
Scott