Ox: Attribute Grammar Compiling System libnew

- update the version of Libtool used to build the Ox distribution to 2.5.4

- update Autoconf generated file due to change [r3633]
- update the version of Libtool used to build the Ox distribution to 2.5.4

- remove support for Solaris/SunOS C/C++ compilers
- remove check for 'libbgc': Solaris version of 'libgc'

- update change summary logs

- remove temporary debugging code

- update Automake generated file due to change [r3521]

- if building 'libnew_dmalloc' with '--enable-debug=no', append '$(LIBNEW_CXXFLAGS)' to 'DMALLOC_CXXFLAGS'
- correct configuration setting override for 'libnew_bdwgc_la_CXXFLAGS'
- append '$(LIBNEW_CXXFLAGS)' to 'libnew_bdwgc_la_CXXFLAGS'
- correct configuration setting override for 'libnew_dmalloc_la_CXXFLAGS'
- append '$(DMALLOC_CXXFLAGS)' to 'libnew_dmalloc_la_CXXFLAGS'

- update Autoconf generated file due to change [r3519]

- add "LT_PREREQ([2.5.3])"
- add 'LIBNEW_CFLAGS' and 'LIBNEW_CXXFLAGS' to hold '-O2' if removed from 'CFLAGS' and 'CXXFLAGS', respectively
- analogous to 'OX_CFLAGS' and 'OX_CXXFLAGS' in the Ox './configure' script

- if environment variable 'MACOSX_DEPLOYMENT_TARGET' is not already set, set it to the macOS version for the currently running system (`sw_vers --productVersion`) to avoid the warning: "ld: warning: -bind_at_load is deprecated on macOS"