Fix DWARF2 testcase failures

[Geoffrey Keating]

Lots of dwarf2 testcases were failing, because current_function_decl
is NULL if no functions are compiled, yet output_line_info gets called
anyway (apparently to work around a HP 'nm' bug).

If there's no function, then last_text_section should be unchanged, so
cfun will never be dereferenced.

Bootstrapped and tested on i686-darwin.

-- 
- Geoffrey Keating <geoffk@apple.com>

===File ~/patches/gcc-dwarfhotcoldfix.patch=================
 2005-04-11  Geoffrey Keating  <geoffk@apple.com>
 
	* dwarf2out.c (output_line_info): Don't try to dereference
	a NULL current_function_decl.

Index: dwarf2out.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/dwarf2out.c,v
retrieving revision 1.582
diff -u -p -u -p -r1.582 dwarf2out.c
--- dwarf2out.c	9 Apr 2005 20:41:44 -0000	1.582
+++ dwarf2out.c	12 Apr 2005 01:29:09 -0000
@@ -7662,7 +7662,7 @@ output_line_info (void)
   long line_delta;
   unsigned long current_file;
   unsigned long function;
-  struct function *cfun = DECL_STRUCT_FUNCTION (current_function_decl);
+  struct function *cfun;
 
   ASM_GENERATE_INTERNAL_LABEL (l1, LINE_NUMBER_BEGIN_LABEL, 0);
   ASM_GENERATE_INTERNAL_LABEL (l2, LINE_NUMBER_END_LABEL, 0);
@@ -7732,6 +7732,11 @@ output_line_info (void)
      a series of state machine operations.  */
   current_file = 1;
   current_line = 1;
+  
+  if (current_function_decl)
+    cfun = DECL_STRUCT_FUNCTION (current_function_decl);
+  else
+    cfun = NULL;
   if (last_text_section == in_unlikely_executed_text
       || (last_text_section == in_named
 	  && last_text_section_name == cfun->unlikely_text_section_name))
============================================================