Convert fatal to perror_with_name in IPA code

Convert fatal to perror_with_name in IPA code

This commit converts four calls to fatal into calls to
perror_with_name.  perror_with_name calls error, which
in IPA terminates with exit (1) rather than longjmp, so
there is no functional change here.

gdb/gdbserver/ChangeLog:

	* tracepoint.c (gdb_agent_init): Replace fatal with
	perror_with_name.
	(initialize_tracepoint): Likewise.