For PR528:

* Consolidate all "install" usage to the install program/script found by
  autoconf which includes the autoconf/install-sh script if necessary
* Change Makefile.rules to not use the -D flag to install but use the
  MKDIR command as necessary.
* Change Makefile.rules to differentiate between installation of executable
  files and regular data files to get the permission modes correct.

llvm-svn: 20294