Test GDB connection to GDBserver with no symbol files

This test exercises the scenarios where we attempt to connect GDB to GDBserver
in standard remote mode, query the symbol file path, attempt to open said
symbol file on GDB's end and fail, causing the connection to drop abruptly.

Regression-tested on x86-64/Ubuntu.

With an unpatched GDB we should see this:

FAIL: gdb.server/connect-with-no-symbol-file.exp: sysroot=: action=permission: connection to GDBserver succeeded (the program is no longer running)
FAIL: gdb.server/connect-with-no-symbol-file.exp: sysroot=: action=delete: connection to GDBserver succeeded (the program is no longer running)
FAIL: gdb.server/connect-with-no-symbol-file.exp: sysroot=target:: action=permission: connection to GDBserver succeeded (the program is no longer running)
FAIL: gdb.server/connect-with-no-symbol-file.exp: sysroot=target:: action=delete: connection to GDBserver succeeded (the program is no longer running)

A patched GDB should have full passes.

gdb/testsuite/ChangeLog:

2016-04-13  Luis Machado  <lgustavo@codesourcery.com>

	* gdb.server/connect-with-no-symbol-file.c: New file.
	* gdb.server/connect-with-no-symbol-file.exp: New file.