linker: inline a single-use constant.

This field is only for backwards compatibility on ILP32 anyway.

Change-Id: If9c29c5065517d246ca70d7d50a070005a5e5a8a
diff --git a/linker/linker_soinfo.h b/linker/linker_soinfo.h
index 3416221..e26942b 100644
--- a/linker/linker_soinfo.h
+++ b/linker/linker_soinfo.h
@@ -154,14 +154,10 @@
   size_t module_id = kTlsUninitializedModuleId;
 };
 
-#if !defined(__LP64__)
-#define SOINFO_NAME_LEN 128
-#endif
-
 struct soinfo {
 #if !defined(__LP64__)
  private:
-  char old_name_[SOINFO_NAME_LEN];
+  char old_name_[128];
 #endif
  public:
   const ElfW(Phdr)* phdr;