TS-1746: disable 128bit compare and swap

Disable the use of 128bit compare and swap that was introduced in
TS-1742. That change was causing crashes in the freelist.

configure.ac

@@ -1108,31 +1108,33 @@ AC_SUBST(need_union_semun)
 AC_MSG_CHECKING(for 128bit CAS support)
 AC_LANG_PUSH([C++])
 
-TS_TRY_COMPILE_NO_WARNING([],[
-    __int128_t x = 0;
-    __sync_bool_compare_and_swap(&x,0,10);
-  ], [
-    AC_MSG_RESULT(yes)
-    has_128bit_cas=1
-  ], [
-      dnl If 128bit CAS fails, try again with the -mcx16 option. GCC needs this;
-      dnl clang doesn't; icc is unknown but presumed sane.
-    __saved_CXXFLAGS="${CXXFLAGS}"
-    TS_ADDTO(CXXFLAGS, [-mcx16])
-    TS_TRY_COMPILE_NO_WARNING([],[
-        __int128_t x = 0;
-        __sync_bool_compare_and_swap(&x,0,10);
-      ], [
-        AC_MSG_RESULT(yes)
-        has_128bit_cas=1
-        dnl Keep CFLAGS and CXXFLAGS in sync.
-        TS_ADDTO(CFLAGS, [-mcx16])
-      ], [
-        AC_MSG_RESULT(no)
-        has_128bit_cas=0
-        CXXFLAGS="${__saved_CXXFLAGS}"
-    ])
-])
+dnl TS_TRY_COMPILE_NO_WARNING([],[
+dnl     __int128_t x = 0;
+dnl     __sync_bool_compare_and_swap(&x,0,10);
+dnl   ], [
+dnl     AC_MSG_RESULT(yes)
+dnl     has_128bit_cas=1
+dnl   ], [
+dnl       dnl If 128bit CAS fails, try again with the -mcx16 option. GCC needs this;
+dnl       dnl clang doesn't; icc is unknown but presumed sane.
+dnl     __saved_CXXFLAGS="${CXXFLAGS}"
+dnl     TS_ADDTO(CXXFLAGS, [-mcx16])
+dnl     TS_TRY_COMPILE_NO_WARNING([],[
+dnl         __int128_t x = 0;
+dnl         __sync_bool_compare_and_swap(&x,0,10);
+dnl       ], [
+dnl         AC_MSG_RESULT(yes)
+dnl         has_128bit_cas=1
+dnl         dnl Keep CFLAGS and CXXFLAGS in sync.
+dnl         TS_ADDTO(CFLAGS, [-mcx16])
+dnl       ], [
+dnl         AC_MSG_RESULT(no)
+dnl         has_128bit_cas=0
+dnl         CXXFLAGS="${__saved_CXXFLAGS}"
+dnl     ])
+dnl ])
+
+has_128bit_cas=0
 
 AC_LANG_POP
 AC_SUBST(has_128bit_cas)