- a partial selection from https://github.com/mrklein/openfoam-os-x
  with adjustments. The primary purpose is to reduce header-level
  incompatibilities and to provide a common set of make rules to allow
  easier patching (or re-integration).

- easier to ensure that flags are consistent

- the USE_OMP preprocessor symbol is also defined with the openmp
  compile flag to allow conditional compilation of openmp-specific
  code.

which may be optionally overridden by version-specific rules.

For example the default rules for gcc on GNU/Linux x86_64 are in the
wmake/rules/linux64Gcc directory.  If there is a need to change any of
the rules for a specific version of gcc, e.g. gcc-4.8.4 the directory
wmake/rules/linux64Gcc48 may be created into which any of the language
files may be provided containing the rules to override the defaults.

- main mplib rules located in GENERAL_RULES with specializations
  (if any) under RULES. Modest change in a few options files, but
  cleans up the rules directories.

  previously in options:
      include $(RULES)/mplib$(WM_MPLIB)

  now in options:
      sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
      sinclude $(RULES)/mplib$(WM_MPLIB)

  For GNU make it would be permissible to write both in a single line.

- otherwise /lib/cpp may need a different library binding than
  currently available and results in this type of error:

  /usr/lib64/gcc/x86_64-suse-linux/4.4/cc1:
  /data/app/OpenFOAM/ThirdParty-1.6.x/platforms/linux64/gcc-4.3.3/lib64/libstdc++.so.6:
  version `GLIBCXX_3.4.11' not found (required by
  /usr/lib64/libppl_c.so.2)

ENH: remove unused flex++ rule for SiCortex that was identical to the
general one anyhow.

	modified:   SiCortex64Gcc/cOpt
	modified:   SunOS64Gcc/cOpt
	modified:   linux64Gcc/c++Opt
	modified:   linux64Gcc/cOpt
	modified:   linux64Gcc/general
	modified:   linux64Gcc42/c++Opt
	modified:   linux64Gcc42/cOpt
	modified:   linuxGcc/c++
	modified:   linuxGcc/cDebug
	modified:   linuxGcc/general
	modified:   linuxIA64Gcc/cOpt