merge bitcoin#27696: Do not define ENABLE_ZMQ when ZMQ is not available

Author: kwvg

configure.ac

@@ -1587,12 +1587,9 @@ dnl ZMQ check
 
 if test "$use_zmq" = "yes"; then
   PKG_CHECK_MODULES([ZMQ], [libzmq >= 4],
-    AC_DEFINE([ENABLE_ZMQ], [1], [Define to 1 to enable ZMQ functions]),
-    [AC_DEFINE([ENABLE_ZMQ], [0], [Define to 1 to enable ZMQ functions])
-    AC_MSG_WARN([libzmq version 4.x or greater not found, disabling])
+    AC_DEFINE([ENABLE_ZMQ], [1], [Define this symbol to enable ZMQ functions]),
+    [AC_MSG_WARN([libzmq version 4.x or greater not found, disabling])
     use_zmq=no])
-else
-  AC_DEFINE_UNQUOTED([ENABLE_ZMQ], [0], [Define to 1 to enable ZMQ functions])
 fi
 
 if test "$use_zmq" = "yes"; then
@@ -1608,6 +1605,8 @@ dnl check if libgmp is present
 AC_CHECK_HEADER([gmp.h],, AC_MSG_ERROR(libgmp headers missing))
 AC_CHECK_LIB([gmp],  [__gmpz_init],GMP_LIBS=-lgmp, AC_MSG_ERROR(libgmp missing))
 
+AM_CONDITIONAL([ENABLE_ZMQ], [test "$use_zmq" = "yes"])
+
 dnl libmultiprocess library check
 
 libmultiprocess_found=no
@@ -1785,8 +1784,6 @@ if test "$bitcoin_enable_qt" != "no"; then
   fi
 fi
 
-AM_CONDITIONAL([ENABLE_ZMQ], [test "$use_zmq" = "yes"])
-
 AC_MSG_CHECKING([whether to build test_dash])
 if test "$use_tests" = "yes"; then
   if test "$enable_fuzz" = "yes"; then