linker: rename load_offset to load_bias.

This patch changes the definition of the 'load_offset' field
in struct soinfo. The field is renamed because it is not the
basic load bias to add to every p_vaddr value read from the ELF
file to get the corresponding memory address.

This also slightly simplifies the relocation code.

+ Fix for proper load_bias computation for relocatable executables.

Change-Id: I72502c75a70751cba324deee7d313ae61f96609e

linker/linker.h

@@ -164,10 +164,9 @@ struct soinfo
     Elf32_Addr gnu_relro_start;
     unsigned gnu_relro_len;
 
-    /* When you read a virtual address from the ELF file, add the load
-     * address (= "base" field) minus this value (= "load_offset") to get the
-     * real, corresponding address in the process' address space */
-    Elf32_Addr load_offset;
+    /* When you read a virtual address from the ELF file, add this
+     * value to get the corresponding address in the process' address space */
+    Elf32_Addr load_bias;
 };