Make the srcdir option value easily accessible in all C tests.
Remove the existing workaround in config-test.

* subversion/tests/svn_test.h
  (svn_test_opts_t): add srcdir member

* subversion/tests/svn_test_main.c
  (main): actually process the already existing srcdir option

* subversion/tests/libsvn_subr/config-test.c
  (test_argc,
   test_argv,
   opt_def,
   srcdir,
   init_params): drop now obsolete globals & utils
  (test_text_retrieval,
   test_boolean_retrieval,
   test_has_section_case_insensitive,
   test_has_section_case_sensitive,
   test_has_option_case_sensitive, 
   test_stream_interface,
   test_read_only_mode): use srcdir from the options struct
  (test_funcs): pass options to everyone that needs them

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1537147 13f79535-47bb-0310-9956-ffa450edef68