Reverting serial-tests for now as it not compatible with older automake version used for automated testing.

configure.ac

@@ -23,7 +23,7 @@
 AC_PREREQ([2.60])
 LT_PREREQ([2.4.0])
 AC_INIT([libmicrohttpd],[0.9.48],[[email protected]])
-AM_INIT_AUTOMAKE([silent-rules] [subdir-objects] [serial-tests])
+AM_INIT_AUTOMAKE([silent-rules] [subdir-objects])
 AC_CONFIG_HEADERS([MHD_config.h])
 AC_CONFIG_MACRO_DIR([m4])
 AH_TOP([#define _GNU_SOURCE  1])