Tests: add TEST_GLOBALS and TEST_GLOBALS_HTTP config chunks. TEST_GLOBALS replaces previously used -g switch. This allows tests to be executed on 0.6.* branch. For compatibility with old tests -g switch will be used if TEST_GLOBALS wasn't expaneded in config. TEST_GLOBALS_HTTP replaces multiple variables (access_log, root, client_body_temp_path, proxy_temp_path, fastcgi_temp_path) previously specified directly in test configs. This change reduce duplication and allows tests to be used with nginx compiled without fastcgi and/or proxy modules (as proxy_temp_path and fastcgi_temp_path are added conditionally).

--- a/smtp-greeting-delay.t
+++ b/smtp-greeting-delay.t
@@ -23,6 +23,8 @@ select STDOUT; $| = 1;
 my $t = Test::Nginx->new()->has('mail')->plan(2)
 	->write_file_expand('nginx.conf', <<'EOF')->run();
 
+%%TEST_GLOBALS%%
+
 master_process off;
 daemon         off;