[cgma-dev] build system changes

[Jason Kraftcheck]

The CGM_LIBS_* make variables and misc. somewhat inconsistent variables for
solid modeling engines have been replaced with the following variable naming
scheme:

*_INCLUDES  : include (-I) flags
*_LIBS      : libraries: either -l flags or paths to the .la files
*_LDFLAGS   : library search paths (-L flags)
*_LTFLAGS   : libtool-specific flags (-R flags)

ACIS_*  : Flags for external ACIS libraries
OCC_*   : Flags for external OCC libraries
CUBIT_* : Flags for linking with libcubiti19.so

So, for example:

ACIS_INCLUDES will be the -I directives for ACIS if CGM is configured with
ACIS, or undefined if CGM is not configured with ACIS.

Further, the following convenience variables are defined for external
libraries that CGM depends on:

CGM_EXT_LIBS = $(ACIS_LIBS) $(OCC_LIBS) $(CUBIT_LIBS)
CGM_EXT_LDFLAGS = $(ACIS_LDFLAGS) $(OCC_LDFLAGS) $(CUBIT_LDFLAGS)
CGM_EXT_LTFLAGS = $(ACIS_LTFLAGS) $(OCC_LTFLAGS) $(CUBIT_LTFLAGS)
CGM_EXT_INCLUDES = $(ACIS_INCLUDES) $(OCC_INCLUDES)

- jason