[GC] Change behavior when reaching external allocation limit

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 60bbdc72b055bb00ddeef64263369faa88f47f93..50132151a59cfca14311b57a6e965e7b6c3a69e7 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -810,6 +810,10 @@ DEFINE_BOOL(manual_evacuation_candidates_selection, false,
             "Test mode only flag. It allows an unit test to select evacuation "
             "candidates pages (requires --stress_compaction).")
 
+// api.cc
+DEFINE_INT(external_allocation_limit_incremental_time, 1,
+           "Time spent in incremental marking steps (in ms) once the external "
+           "allocation limit is reached")
 
 //
 // Dev shell flags