message: build, qt: Fix regression introduced in
  Due to the ill-formed code _BITCOIN_QT_CHECK_STATIC_PLUGIN never fails.
diff: @@ -306,7 +306,10 @@ AC_DEFUN([_BITCOIN_QT_CHECK_STATIC_PLUGIN], [
  AC_MSG_CHECKING([for $1 ($2)])
  CHECK_STATIC_PLUGINS_TEMP_LIBS="$LIBS"
  LIBS="$2${qt_lib_suffix} $QT_LIBS $LIBS"
  - AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <QtPlugin> Q_IMPORT_PLUGIN($1)]])],
  + AC_LINK_IFELSE([AC_LANG_PROGRAM([[
  + #include <QtPlugin>
  + Q_IMPORT_PLUGIN($1)
  + ]])],
  [AC_MSG_RESULT([yes]); QT_LIBS="$2${qt_lib_suffix} $QT_LIBS"],
  [AC_MSG_RESULT([no]); BITCOIN_QT_FAIL([$1 not found.])])
  LIBS="$CHECK_STATIC_PLUGINS_TEMP_LIBS"
  