Fix breakpoint condition that use member variables.

	Fix breakpoint condition that use member variables.
        * valops.c (check_field): Remove.
        (check_field_in): Rename to check_field.
        (value_of_this): Use la_name_of_this.
        * value.h (check_field): Adjust prototype.

        * language.h (la_value_of_this): Rename to la_name_of_this.
        * language.c (unknown_language_defn): Specify "this" for
        name_of_this.
        (auto_language_defn): Likewise.
        (local_language_defn): Likewise.
        * ada-lang.c (ada_language_defn): Adjust comment.
        * c-lang.c (c_language_defn): Adjust comment.
        (cplus_language_defn): Specify "this" for name_of_this.
        (asm_language_defn): Adjust comment.
        (minimal_language_defn): Adjust comment.
        * f-lang.c (f_language_defn): Specify NULL for name_of_this.
        * jv-lang.c (java_language_defn): Specify "this" for name_of_this.
        * m2-lang.c (m2_language_defn): Specify "this" for name_of_this.
        * objc-lang.c (objc_language_defn): Specify "self" for
        name_of_this.
        * p-lang.c (pascal_language_defn): Specify "this" for
        name_of_this.
        * scm-lang.c (scm_language_defn): Specify NULL for name_of_this.

        * symtab.c (lookup_symbol_aux): Lookup "this" in the
        proper scope, and check for field in type of "this", without
        trying to create a value.