Add test for load command
    
    There doesn't seem to by any test for the load command.  I suggest to
    add this test, so that we can have a minimum of confidence we don't
    break it completely while refactoring the code that implements it.
    
    gdb/testsuite/ChangeLog:
    
    	* gdb.base/load-command.c: New file.
    	* gdb.base/load-command.exp: New file.
    	* lib/gdb.exp (gdb_is_target_remote_prompt): Rename to...
    	(gdb_is_target_1): ...this, and generalize for other targets
    	than just remote.
    	(gdb_is_target_remote): Use gdb_is_target_1.
    	(gdb_is_target_native): use gdb_is_target_1.