build: add --with-qt-translationdir to configure for use with static qt

src/m4/bitcoin_qt.m4

@@ -62,6 +62,7 @@ AC_DEFUN([BITCOIN_QT_INIT],[
   AC_ARG_WITH([qt-incdir],[AS_HELP_STRING([--with-qt-incdir=INC_DIR],[specify qt include path (overridden by pkgconfig)])], [qt_include_path=$withval], [])
   AC_ARG_WITH([qt-libdir],[AS_HELP_STRING([--with-qt-libdir=LIB_DIR],[specify qt lib path (overridden by pkgconfig)])], [qt_lib_path=$withval], [])
   AC_ARG_WITH([qt-plugindir],[AS_HELP_STRING([--with-qt-plugindir=PLUGIN_DIR],[specify qt plugin path (overridden by pkgconfig)])], [qt_plugin_path=$withval], [])
+  AC_ARG_WITH([qt-translationdir],[AS_HELP_STRING([--with-qt-translationdir=PLUGIN_DIR],[specify qt translation path (overridden by pkgconfig)])], [qt_translation_path=$withval], [])
   AC_ARG_WITH([qt-bindir],[AS_HELP_STRING([--with-qt-bindir=BIN_DIR],[specify qt bin path])], [qt_bin_path=$withval], [])
 
   AC_ARG_WITH([qtdbus],
@@ -69,6 +70,8 @@ AC_DEFUN([BITCOIN_QT_INIT],[
     [enable DBus support (default is yes if qt is enabled and QtDBus is found)])],
     [use_dbus=$withval],
     [use_dbus=auto])
+
+  AC_SUBST(QT_TRANSLATION_DIR,$qt_translation_path)
 ])
 
 dnl Find the appropriate version of Qt libraries and includes.