gdb/testsuite/gdb.base/break.exp: split test_break

Move all the remaining tests to a single test_break proc.  It's a bit
big, but all of these are kind of tied together.  The procs starts by
setting breakpoints, checks that we can see them in "info breakpoints",
and tries stopping on them.

Move all the "set bp_locationX" calls together at the top.

Change-Id: Id05f98957e1a3462532d2dbd577cd0a7c7263900
Approved-By: Kevin Buettner <kevinb@redhat.com>