[OS X TeX] Plain-TeX in landscape does not work in TeXlive2012

[Basil Grammaticos]

I have a problem I have with plain-TeX and landscape. 
Till now I have been using plain TeX in landscape 
mode in order to prepare my presentations. 
For this I need graphicxland.tex and miniltx.tex. 

Yesterday I installed the 2012 TeXlive distribution and nothing works any more. 
The message I get is that at
/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/ifpdf.sty
there is a name clash and \ifpdf is already defined.

Here is the full console output

This is pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012)
 \write18 enabled.
entering extended mode
(./LinearOneTwo.tex
(/usr/local/texlive/2012/texmf-config/tex/generic/config/pdftexconfig.tex)
(./graphicxland.tex (./miniltx.tex) (./graphicx.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/graphics/keyval.sty)
(/usr/local/texlive/2012/texmf-dist/tex/latex/graphics/graphics.sty
(/usr/local/texlive/2012/texmf-dist/tex/latex/graphics/trig.sty)
(/usr/local/texlive/2012/texmf-dist/tex/latex/latexconfig/graphics.cfg
(/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/pdftexcmds.sty
(/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/infwarerr.sty)
(/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/ifluatex.sty)
(/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/ltxcmds.sty)
(/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/ifpdf.sty
/usr/local/texlive/2012/texmf-dist/tex/generic/oberdiek/ifpdf.sty:173: ifp
df: Name clash, \ifpdf is already defined.
\PackageError ...\errhelp {#3}\errmessage {#1: #2}
                                                  
l.173     }
           %

I installed the TeXlive 2010 distribution again and everything works. 
So there must be something that miniltx is using 
and which has been deleted or displaced. 

Could anybody help me with this?