Refine the CPPLINT script to not report a __CPROVER_ misuse false positive

Author: angelhof

scripts/cpplint.py

@@ -4614,7 +4614,7 @@ def Check__CPROVER_(filename, clean_lines, linenum, error):
     error: The function to call with any errors found.
   """
   line = clean_lines.lines[linenum]
-  match = Match(r'.*__CPROVER_.*', line)
+  match = Match(r'.*\"__CPROVER_.*\"', line)
   if match:
     error(filename, linenum, 'build/deprecated', 4,
           'use CPROVER_PREFIX instead of __CPROVER_')