[patch] testcase for exception table labels

[DJ Delorie]

> > No, please use .C to be consistent with the rest of the testsuite.
> 
> There should be some with .cpp extension, otherwise we won't be testing 
> that it works.   Consistency in a testsuite is not a virtue; the idea 
> should be to test as many things as possible.

Plus, the .c/.C difference vanishes on case-insensitive file systems,
like DJGPP, Cygwin, or MinGW.  DJGPP, at least, normally uses .cc for
C++ files because of this.