[RFA/testsuite] Allow __libc_start_main above main in annota1.exp

[Michael Elizabeth Chastain]

BTW, the annotation interface is deprecated (see the NEWS file
in gdb 5.1.1).  I'm in favor of maintaining test scripts for
deprecated features for a while, but I don't feel an urge to
solve the "giant annotation line" problem.

Andrew or anyone, can you say how long the annotation interface
is going to stay around?

Michael C