If the .c and .h file already exist, and they have not changed, use the 
original versions of the files, so as to avoid rebuilding files when not
necessary.  Also fixes a potential SMP/Parallel build problem when one 
make process runs compile_et to generate the .h file, and a partially
generated .c file is compiled by another make process.  (Addresses
Sourceforge Bug: #1157933)

3 files changed