RFA: Fix pch/system-1.c failures for systems with non-trivial BUILD_VA_LIST_TYPE

[Joern Rennecke <joern dot rennecke at superh dot com>]

I have found that pch/system-1.c fails on sh-elf because
the function that is called by BUILD_VA_LIST_TYPE generates
some declarations which end up in the debugging output for
this testcase.  toplev.c has previously set the input filename
to that of the main file - which is different when you compile
a header than when you do an ordinary source compilation.
This causes an anadorned "system-1.h" to be considered among
the source files in the pch case (even though it does nothing
but include other header files).  When dwarf2out sees an input
file without a dir separator, it puts the current working directory
in the list of directories to search.

-- 
--------------------------
SuperH (UK) Ltd.
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2003-06-02  J"orn Rennecke <joern.rennecke@superh.com>

	* c-decl.c (c_init_decl_processing): Clear input_file_name
	while building common nodes.
	* dwarf2out.c (gen_compile_unit_die, dwarf2out_finish):
	Don't add working directory for <built-in> .

Index: c-decl.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/c-decl.c,v
retrieving revision 1.390
diff -p -r1.390 c-decl.c
*** c-decl.c	22 May 2003 19:39:13 -0000	1.390
--- c-decl.c	2 Jun 2003 21:08:58 -0000
*************** c_init_decl_processing ()
*** 2266,2271 ****
--- 2266,2272 ----
  {
    tree endlink;
    tree ptr_ftype_void, ptr_ftype_ptr;
+   const char *save_input_filename;
  
    /* Adds some ggc roots, and reserved words for c-parse.in.  */
    c_parse_init ();
*************** c_init_decl_processing ()
*** 2278,2283 ****
--- 2279,2289 ----
    /* Make the binding_level structure for global names.  */
    pushlevel (0);
    global_binding_level = current_binding_level;
+   /* Declarations from c_common_nodes_and_builtins must not be associated
+      with this input file, lest we get differences between using and not
+      using preprocessed headers.  */
+   save_input_filename = input_filename;
+   input_filename = NULL;
  
    build_common_tree_nodes (flag_signed_char);
  
*************** c_init_decl_processing ()
*** 2304,2309 ****
--- 2310,2317 ----
    ptr_ftype_ptr
      = build_function_type (ptr_type_node,
  			   tree_cons (NULL_TREE, ptr_type_node, endlink));
+ 
+   input_filename = save_input_filename;
  
    pedantic_lvalues = pedantic;
  
Index: dwarf2out.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/dwarf2out.c,v
retrieving revision 1.426
diff -p -r1.426 dwarf2out.c
*** dwarf2out.c	20 May 2003 01:49:11 -0000	1.426
--- dwarf2out.c	2 Jun 2003 21:08:59 -0000
*************** gen_compile_unit_die (filename)
*** 11491,11497 ****
    if (filename)
      {
        add_name_attribute (die, filename);
!       if (filename[0] != DIR_SEPARATOR)
  	add_comp_dir_attribute (die);
      }
  
--- 11491,11497 ----
    if (filename)
      {
        add_name_attribute (die, filename);
!       if (filename[0] != DIR_SEPARATOR && strcmp (filename, "<built-in>") != 0)
  	add_comp_dir_attribute (die);
      }
  
*************** dwarf2out_finish (filename)
*** 13082,13088 ****
      {
        size_t i;
        for (i = 1; i < VARRAY_ACTIVE_SIZE (file_table); i++)
! 	if (VARRAY_CHAR_PTR (file_table, i)[0] != DIR_SEPARATOR)
  	  {
  	    add_comp_dir_attribute (comp_unit_die);
  	    break;
--- 13082,13089 ----
      {
        size_t i;
        for (i = 1; i < VARRAY_ACTIVE_SIZE (file_table); i++)
! 	if (VARRAY_CHAR_PTR (file_table, i)[0] != DIR_SEPARATOR
! 	    && strcmp (VARRAY_CHAR_PTR (file_table, i), "<built-in>") != 0)
  	  {
  	    add_comp_dir_attribute (comp_unit_die);
  	    break;