This breaks backwards compatibility of cache hashes, which means that
old cache entries will not give cache hits.
The reason for the change is to make it easier to re-use the same
hashing order for Direct Mode and Preprocessor Mode caching.
There was a typo in the make_preprocessor_cmd() function that
incorrectly looked for ---preproc_* (notice the three dashes).
This fix ensures that the TI C6X wrapper correctly detects and removes
--preproc_* arguments (and not only their short counterparts).
m