Function: comint-check-source

Check whether to save buffers visiting file FNAME.
Prior to loading or compiling (or otherwise processing) a file (in the CMU
process-in-a-buffer modes), this function can be called on the filename.
If the file is loaded into a buffer, and the buffer is modified, the user
is queried to see if he wants to save the buffer before proceeding with
the load or compile. (fn FNAME)