Remove dead code in testsuite

Remove dead code in testsuite

This patch removes cases from the testsuite that are not posssibly used.  The
messages "Catch of * not yet implemented" were removed here:

https://www.sourceware.org/ml/gdb-patches/2004-01/msg00679.html

I changed the regexp at the same time to match the string more closely.

gdb/testsuite/ChangeLog:

	* gdb.base/break.exp: Remove dead code.
	* gdb.base/sepdebug.exp: Likewise.