Table build logic is assuming ".o" extension for object files

[jphickey]

Describe the bug
The new scripts that are used to build table files assume a ".o" extension on object files. This is not always the case, as some other systems use ".obj".

To Reproduce
Build using the vxworks 6.9 toolchain combined with the VxWorks platform module - this sets up for an ".obj" extension. Table file generation will fail due to a missing .o file.

Expected behavior
Should build successfully.

System observed on:
VxWorks 6.9 (GSFC build machine)

Additional context
The variable ${CMAKE_C_OUTPUT_EXTENSION} should be used here.

Reporter Info
Joseph Hickey, Vantage Systems, Inc.