this makes it so that a flag is set if either an objective-c
compilation unit is found,
or the user goes 'set language objective-c' in the case where debug
symbols are absent.

2010-10-05  Matt Rice  <ratmice@gmail.com>

        * defs.h: Add comment.
        * dwarf2read.c (set_cu_language): Notice that a language has been
        seen.
        * language.c (set_language): Ditto.
        (mask_for_language, language_has_cu_loaded): New Functions.
        (set_language_has_cu_loaded): Ditto.
        * language.h: Declare new functions.
        * linespec.c (decode_line_1): Don't lookup objective-c methods
        unless objective-c has been seen.