Make linker-created symbols relocatable where appropriate.

Linker-created symbols like __ehdr_start, __etext, __edata, and end
should be relocatable, not absolute.


2016-12-21  Cary Coutant  <ccoutant@gmail.com>

gold/
	* output.cc (Output_segment::first_section): Return NULL if there are
	no sections in the segment.
	* output.h (Output_segment::first_section_load_address): Assert that
	first section is not NULL.
	* symtab.cc (Symbol_table::sized_write_globals): Attach linker-created
	segment-relative symbols to first section of the segment.


diff --git a/gold/output.cc b/gold/output.cc
index cf934fb..64df3e8 100644
--- a/gold/output.cc
+++ b/gold/output.cc
@@ -4801,7 +4801,7 @@ Output_segment::first_section() const
 	    return (*p)->output_section();
 	}
     }
-  gold_unreachable();
+  return NULL;
 }
 
 // Return the number of Output_sections in an Output_segment.
diff --git a/gold/output.h b/gold/output.h
index 9083b5a..2b8f0c8 100644
--- a/gold/output.h
+++ b/gold/output.h
@@ -4741,6 +4741,7 @@ class Output_segment
   first_section_load_address() const
   {
     const Output_section* os = this->first_section();
+    gold_assert(os != NULL);
     return os->has_load_address() ? os->load_address() : os->address();
   }
 
diff --git a/gold/symtab.cc b/gold/symtab.cc
index 6865190..35989f0 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -3120,7 +3120,14 @@ Symbol_table::sized_write_globals(const Stringpool* sympool,
 	  break;
 
 	case Symbol::IN_OUTPUT_SEGMENT:
-	  shndx = elfcpp::SHN_ABS;
+	  {
+	    Output_segment* oseg = sym->output_segment();
+	    Output_section* osect = oseg->first_section();
+	    if (osect == NULL)
+	      shndx = elfcpp::SHN_ABS;
+	    else
+	      shndx = osect->out_shndx();
+	  }
 	  break;
 
 	case Symbol::IS_CONSTANT: