gdb: remove LA_VALUE_PRINT macro

gdb: remove LA_VALUE_PRINT macro

Remove the LA_VALUE_PRINT macro, and replace its uses with direct
calls to the value_print member function on an appropriate language.

In the global 'value_print' function, we call the value_print method
on the current_language, this is a direct inline replacement of the
old LA_VALUE_PRINT macro.

However, in ada-lang.c, and language.c the macro was being used
within the print_array_index member function of a language class.  In
these cases we now call the value_print member function of the current
language class.

In theory, when we are inside (for example) the
ada_language::print_array_index function the current_language should
always be set to Ada, so this change should have no effect.  However,
if we ever could get into ada_language::print_array_index with the
current language set to something else (which I think would have been
a bug) then we would now see a change in behaviour.  I couldn't find
any cases where this happened though.

There should be no user visible changes after this commit, but it is
not impossible in some edge cases.

gdb/ChangeLog:

	* ada-lang.c (ada_language::print_array_index): Call value_print
	directly.
	* language.c (language_defn::print_array_index): Likewise.
	* language.h (LA_VALUE_PRINT): Delete.
	* valprint.c (value_print): Call value_print on the
	current_language directly.