Avoid printing generic and duplicated "checking for QT" during ./configure

Print "checking for QT4" and "checking for QT5" instead

build-aux/m4/bitcoin_qt.m4

@@ -399,17 +399,17 @@ AC_DEFUN([_BITCOIN_QT_FIND_LIBS_WITH_PKGCONFIG],[
     qt4_modules="QtCore QtGui QtNetwork"
     BITCOIN_QT_CHECK([
       if test x$bitcoin_qt_want_version = xqt5 || ( test x$bitcoin_qt_want_version = xauto && test x$auto_priority_version = xqt5 ); then
-        PKG_CHECK_MODULES([QT], [$qt5_modules], [QT_INCLUDES="$QT_CFLAGS"; have_qt=yes],[have_qt=no])
+        PKG_CHECK_MODULES([QT5], [$qt5_modules], [QT_INCLUDES="$QT5_CFLAGS"; QT_LIBS="$QT5_LIBS" have_qt=yes],[have_qt=no])
       elif test x$bitcoin_qt_want_version = xqt4 || ( test x$bitcoin_qt_want_version = xauto && test x$auto_priority_version = xqt4 ); then
-        PKG_CHECK_MODULES([QT], [$qt4_modules], [QT_INCLUDES="$QT_CFLAGS"; have_qt=yes], [have_qt=no])
+        PKG_CHECK_MODULES([QT4], [$qt4_modules], [QT_INCLUDES="$QT4_CFLAGS"; QT_LIBS="$QT4_LIBS" ; have_qt=yes], [have_qt=no])
       fi
 
       dnl qt version is set to 'auto' and the preferred version wasn't found. Now try the other.
       if test x$have_qt = xno && test x$bitcoin_qt_want_version = xauto; then
         if test x$auto_priority_version = xqt5; then
-          PKG_CHECK_MODULES([QT], [$qt4_modules], [QT_INCLUDES="$QT_CFLAGS"; have_qt=yes; QT_LIB_PREFIX=Qt; bitcoin_qt_got_major_vers=4], [have_qt=no])
+          PKG_CHECK_MODULES([QT4], [$qt4_modules], [QT_INCLUDES="$QT4_CFLAGS"; QT_LIBS="$QT4_LIBS" ; have_qt=yes; QT_LIB_PREFIX=Qt; bitcoin_qt_got_major_vers=4], [have_qt=no])
         else
-          PKG_CHECK_MODULES([QT], [$qt5_modules], [QT_INCLUDES="$QT_CFLAGS"; have_qt=yes; QT_LIB_PREFIX=Qt5; bitcoin_qt_got_major_vers=5], [have_qt=no])
+          PKG_CHECK_MODULES([QT5], [$qt5_modules], [QT_INCLUDES="$QT5_CFLAGS"; QT_LIBS="$QT5_LIBS" ; have_qt=yes; QT_LIB_PREFIX=Qt5; bitcoin_qt_got_major_vers=5], [have_qt=no])
         fi
       fi
       if test x$have_qt != xyes; then