Fix linker compilation when STATS is set

Test: Compiles with STATS set in linker_debug.h
Change-Id: I8ea6ca9a61ad316473dab51999885008f2721cee
diff --git a/linker/linker.h b/linker/linker.h
index 0f30946..a26b79d 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -99,6 +99,8 @@
 
 void count_relocation(RelocationKind kind);
 
+void print_linker_stats();
+
 soinfo* get_libdl_info(const soinfo& linker_si);
 
 soinfo* find_containing_library(const void* p);