Deprecate and remove from the build an unused 2-line utility function

Author: martin

src/pointer-analysis/Makefile

@@ -1,6 +1,5 @@
 SRC = add_failed_symbols.cpp \
       goto_program_dereference.cpp \
-      rewrite_index.cpp \
       show_value_sets.cpp \
       value_set.cpp \
       value_set_analysis.cpp \

src/pointer-analysis/rewrite_index.h

@@ -16,7 +16,7 @@ class dereference_exprt;
 class index_exprt;
 
 // rewrite a[i] to *(a+i)
-
+DEPRECATED(SINCE(2022, 07, 23, "implement the transform directly"))
 dereference_exprt rewrite_index(const index_exprt &index_expr);
 
 #endif // CPROVER_POINTER_ANALYSIS_REWRITE_INDEX_H