R: shared lib prefix simplification

[John W. Eaton]

On  7-May-2009, John W. Eaton wrote:

| On  7-May-2009, Marco Atzeri wrote:
| 
| | what do you means with all instance ?
| | We agreed on:
| | 
| |  $(SHLPRE)octinterp.$(SHLEXT)
| |  $(SHLLIBPRE)octinterp.$(SHLLIB)
| |  $(SHLBINPRE)octinterp.$(SHLBIN)
| | 
| | so with SHLLIB we should maintain SHLIBPRE.
| | Or I missed some SHLEXT istance ?
| 
| OK, then I probably screwed it up.

I think I've undone my incorrect changes.  Can you update and check to
see whether it is now the way you expect?  Is SHLPRE always properly
paired with SHLEXT, and SHLLIBPRE always properly paired with SHLLIB?

Also, why do we set the prefixes to "" for MSVC but not MinGW?

Thanks,

jwe