Eliminate shared global variables (not constants) in our C tests by
simply declaring them locally in each tests that needs them.

* subversion/tests/libsvn_subr/string-test.c
  (a, b, c): drop these global variables
  (test1,
   test2,
   test3,
   test4,
   test5,
   test6,
   test7,
   test8,
   test9,
   test_find_char_backward,
   test13,
   test14,
   test15,
   test16,
   test17,
   test_first_non_whitespace,
   test21,
   test_stringbuf_unequal,
   test_stringbuf_insert,
   test_stringbuf_remove,
   test_stringbuf_replace): declare variables locally

* subversion/tests/libsvn_subr/mergeinfo-test.c
  (info1, info2): drop these global variables
  (test_parse_combine_rangeinfo,
   test_parse_broken_mergeinfo,,
   test_mergeinfo_intersect,
   test_merge_mergeinfo,
   test_rangelist_to_string,
   test_mergeinfo_to_string): declare variables locally


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1544728 13f79535-47bb-0310-9956-ffa450edef68