Add CPROVER prefix to memory primitives produced by expr2c

[qinheping]

Memory primitives __CPROVER_POINTER_OBJECT, __CPROVER_OBJECT_SIZE, and __CPROVER_POINTER_OFFSET converted to C using expr2c are now without __CPROVER prefix, which is not consistent with their usage in C.

Also, history primitives __CPROVER_loop_entry is missing.

[codecov]

Codecov Report

Base: 78.47% // Head: 78.47% // No change to project coverage 👍

Coverage data is based on head (954df79) compared to base (78fb718).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #7454   +/-   ##
========================================
  Coverage    78.47%   78.47%           
========================================
  Files         1662     1662           
  Lines       191045   191045           
========================================
  Hits        149931   149931           
  Misses       41114    41114           

Impacted Files	Coverage Δ
src/ansi-c/expr2c.cpp	67.88% <ø> (ø)

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