Tests: use error.log instead of nginx-error.log.

lib/Test/Nginx.pm

diff --git a/lib/Test/Nginx.pm b/lib/Test/Nginx.pm
index 1f9e300..d90a553 100644
--- a/lib/Test/Nginx.pm
+++ b/lib/Test/Nginx.pm
@@ -56,7 +56,7 @@
 	if ($pid == 0) {
 		exec('../nginx/objs/nginx', '-c', "$testdir/nginx.conf", '-g',
 			"pid $testdir/nginx.pid; "
-			. "error_log $testdir/nginx-error.log debug;")
+			. "error_log $testdir/error.log debug;")
 			or die "Unable to exec(): $!\n";
 	}