Hi,

Revised patch for supporting DW_AT_calling_convention. This helps GDB
identify the "main" program for languages that do not have a starting
subroutine called "main". It adds a new API set for keeping track of the
symbol associated with "main". Note that there are 3 checks for
DW_AT_calling_convention. They are all necessary as they are detected at
different times when processing program debug information.

2002-07-10 Petr Sorfa (petrs@caldera.com)

        *  dwarf2read.c (read_subroutine_type): Expanded to recognize
           the DW_AT_calling_convention DWARF attribute and for
           DW_CC_program and calls set_main_name ().
           (read_partial_die): Now recognizes the
           DW_AT_calling_convention attribute and calls set_main_name().
           (new_symbol): Checks whether the new symbol has a die entry
           for DW_AT_calling_convention and calls set_main_symbol() for
           DW_CC_program.

        *  symtab.h (set_main_symbol):
           (get_main_symbol):
           (is_main_symbol): Added extern prototypes for these dealing
           with setting the ``main'' symbol.

        *  symtab.c (symbol_of_main): New static variable that points to
           the current ``main'' symbol.
           (set_main_symbol): New function that assigns a value to
           symbol_of_main.
           (get_main_symbol): Returns the value of symbol_of_main.
           (is_main_symbol): Determines whether a given symbol is
           equivalent to the "main" symbol.