print_symbol_info patch for source code not current language

[Jim Blandy]

>    Using my pascal patched GDB 
> with a executable that links both C and pascal code I noticed that
>   all the functions where printed out using the current language,
> even if in automatic mode !!
>   C functions printed out in pascal conventions are really uggly !!
> (And I don't say that because I prefer C,
> remember that I am a codevelopper of Free Pascal
> and that I started coding C just to be able to patch GDB !)
> 
>   Shouldn't we use the language of source if known at least if
> the current language mode is auto ??
> 
>   This short patch to symtab.c solve this problem

This looks good!

However, saving, setting, and restoring the current language is
somewhat messy.  Note that the definition of type_print just calls
LA_PRINT_TYPE, which calls current_language->la_print_type.  Your code
could simply determine the appropriate language, L, and then call
L->la_print_type directly, instead of print_type.

I don't know if it is possible for symbols to have language_auto as
their language.  It is probably best to handle that case somehow, even
if it never arises.