roll back to v2_4_2 tag rather than tip of ruby_2_4 branch

Author: Charlie Somerville

configure.in

@@ -1403,15 +1403,13 @@ AC_ARG_WITH([gmp],
 AS_IF([test "x$with_gmp" != xno],
   [AC_CHECK_HEADERS(gmp.h)
    AS_IF([test "x$ac_cv_header_gmp_h" != xno],
-     AC_SEARCH_LIBS([__gmpz_init], [gmp],
-       [AC_DEFINE(HAVE_LIBGMP, 1)]))])
+     AC_SEARCH_LIBS([__gmpz_init], [gmp]))])
 
 AC_ARG_WITH([jemalloc],
   [AS_HELP_STRING([--with-jemalloc],[use jemalloc allocator])],
   [with_jemalloc=$withval], [with_jemalloc=no])
 AS_IF([test "x$with_jemalloc" = xyes],[
-  AC_SEARCH_LIBS([malloc_conf], [jemalloc],
-    [AC_DEFINE(HAVE_LIBJEMALLOC, 1)], [with_jemalloc=no])
+  AC_SEARCH_LIBS([malloc_conf], [jemalloc], [], [with_jemalloc=no])
   AC_CHECK_HEADER(jemalloc/jemalloc.h, [
     AC_DEFINE(RUBY_ALTERNATIVE_MALLOC_HEADER, [<jemalloc/jemalloc.h>])
   ])

version.h

@@ -1,10 +1,10 @@
-#define RUBY_VERSION "2.4.3"
-#define RUBY_RELEASE_DATE "2017-09-15"
-#define RUBY_PATCHLEVEL 200
+#define RUBY_VERSION "2.4.2"
+#define RUBY_RELEASE_DATE "2017-09-14"
+#define RUBY_PATCHLEVEL 198
 
 #define RUBY_RELEASE_YEAR 2017
 #define RUBY_RELEASE_MONTH 9
-#define RUBY_RELEASE_DAY 15
+#define RUBY_RELEASE_DAY 14
 
 #include "ruby/version.h"