Revision 1818807

Lower minimum required version of LZ4 to r120

* INSTALL
  (C.22.LZ4): Change minimum version to r120

* build/ac-macros/lz4.m4
  (SVN_LZ4): Change minimum version in "not found" error message to r120
  (SVN_LZ4_STD): Adjust version check to handle both version schemes and use
    120 as the minimum version.  Replace check for LZ4_versionString symbol
    with LZ4_versionNumber.
  (SVN_LZ4_PREFIX): Replace check for LZ4_decompress_safe symbol with
    LZ4_versionNumber.