This patch adds a protection against rootcint accidentally erasing its input.  In particular the case:
This patch adds a protection against rootcint accidentally erasing its
input.  In particular the case:

   rootcint dict.cxx -c header.h linkdef.h

will now fail if either dict.cxx or dict.h already exist (so far it was
only checking dict.cxx)
And

   rootcint -f file.cxx -c file.h linkdef.h

will fail with the message:

  Error: rootcint: output file file.h would overwrite one of the input files!


git-svn-id: ecbadac9c76e8cf640a0bca86f6bd796c98521e3@11847 27541ba8-7e3a-0410-8455-c3a389f83636

dawehner/root,bbannier/ROOT,bbannier/ROOT,dawehner/root,dawehner/root,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,dawehner/root,bbannier/ROOT,dawehner/root,dawehner/root,dawehner/root,bbannier/ROOT,dawehner/root