print help from all modules in top-level builds

this is rather hacky. a proper solution would auto-generate help from
the command line argument definitions, at the cost of needing to
bootstrap qmake first.

Change-Id: Iada6e25d5b31d7db0595309887f2d13295bbc1e3
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

configure

@@ -522,6 +522,16 @@ done
 
 if [ "$OPT_HELP" = "yes" ]; then
     cat $relpath/config_help.txt
+    if [ -n "$CFG_TOPLEVEL" ]; then
+        IFS='
+'
+        for i in $relpathMangled/qt*/config_help.txt; do
+            if [ x"$i" != x"$relpath/config_help.txt" ]; then
+                echo
+                cat "$i"
+            fi
+        done
+    fi
     exit 0
 fi
 

configure.bat

@@ -84,6 +84,16 @@ goto doneargs
 
 :help
     type %QTSRC%\config_help.txt
+    if %TOPLEVEL% == true (
+        for /d %%p in ("%TOPQTSRC%"\qt*) do (
+            if not "%%p" == "%QTSRC%" (
+                if exist "%%p\config_help.txt" (
+                    echo.
+                    type "%%p\config_help.txt"
+                )
+            )
+        )
+    )
     exit /b 1
 
 :redo