Don't "sudo install" allowing for a non-root build process.
Removed VMCS_INSTALL_PREFIX and vmcs_root from install() commands.
  It is unclear why absolute paths are actually used here since the prefixes used by install() for relative paths are exactly the current source
  directory (stored in vmcs_root) and the install prefix (stored in VMCS_INSTALL_PREFIX).
This also fixes the problem of interface/vmcs_host/khronos/IL being installed twice due to pattern matching problems using "PATTERN EXCLUDE".
Removed remaining uses of VMCS_INSTALL_PREFIX and vmcs_root.