Fix gdb.ada/bp_c_mixed_case.exp (PR gdb/22670)
    
    The problem here is that we were using the user-provided lookup name
    literally for linkage name comparisons.  I.e., "<MixedCase>" with the
    "<>"s included.  That obviously can't work since the "<>" are not
    really part of the linkage name.  The original idea was that we'd use
    the symbol's language to select the right symbol name matching
    algorithm, but that doesn't work for Ada because it's not really
    possible to unambiguously tell from the linkage name alone whether
    we're dealing with Ada symbols, so Ada minsyms end up with no language
    set, or sometimes C++ set.  So fix this by treating Ada mode specially
    when determining the linkage name to match against.
    
    gdb/ChangeLog:
    yyyy-mm-dd  Pedro Alves  <palves@redhat.com>
    
    	PR gdb/22670
    	* minsyms.c (linkage_name_str): New function.
    	(iterate_over_minimal_symbols): Use it.
    
    gdb/testsuite/ChangeLog:
    yyyy-mm-dd  Pedro Alves  <palves@redhat.com>
    
    	PR gdb/22670
    	* gdb.ada/bp_c_mixed_case.exp: Remove setup_kfail calls.