configure: fix cross-module library uses

this went unnoticed, because the only cross-module 'use' so far is that
of egl, for which the code path provided for modular builds happens to
(mostly) work due to the specs already providing the library definition.

amends cc842ca4.

Change-Id: I58c638d896eabd26f27d5cd90e3a7f8eeece9bc0
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

mkspecs/features/qt_configure.prf

@@ -757,7 +757,7 @@ defineTest(qtConfTestPrepare_compile) {
             libConfig = $${currentConfig}
             qtConfHandleLibrary($$u)
         } else {
-            for (d, QMAKE_CONFIG_DEPS) {
+            for (d, QMAKE_LIBRARY_DEPS) {
                 contains($${d}.libraries._KEYS_, $$u) {
                     libConfig = $$d
                     break()
@@ -1813,8 +1813,6 @@ for(ever) {
     jsonFile = $$thisDir/configure.json
     priFile = $$thisDir/configure.pri
 
-    allConfigs += $$currentConfig
-
     # load configuration data
     configure_data = $$cat($$jsonFile, blob)
     !parseJson(configure_data, $$currentConfig): \
@@ -1822,6 +1820,21 @@ for(ever) {
     exists($$priFile): \
         !include($$priFile): error()
 
+    # only configs which contain more than just subconfigs are saved for later.
+    $${currentConfig}._KEYS_ -= subconfigs
+    !isEmpty($${currentConfig}._KEYS_) {
+        allConfigs += $$currentConfig
+        contains($${currentConfig}._KEYS_, libraries) {
+            qtConfSetupLibraries()
+            # this ensures that references in QMAKE_LIBRARY_DEPS are unique.
+            qtConfSetModuleName()
+            ex = $$eval(config.modules.$${currentModule})
+            !isEmpty(ex): \
+                error("Module $$currentModule is claimed by both $$currentConfig and $${ex}.")
+            config.modules.$${currentModule} = $$currentConfig
+        }
+    }
+
     # prepend all subconfigs to files to keep a depth first search order
     subconfigs =
     for(n, $${currentConfig}.subconfigs._KEYS_) {
@@ -1836,9 +1849,6 @@ for(ever) {
     configsToProcess = $$subconfigs $$configsToProcess
 }
 
-for (currentConfig, allConfigs): \
-    qtConfSetupLibraries()
-
 QMAKE_SAVED_ARGS = $$QMAKE_EXTRA_ARGS
 QMAKE_REDO_CONFIG = false
 qtConfParseCommandLine()
@@ -1948,11 +1958,15 @@ for (currentConfig, allConfigs) {
 
     # correctly setup dependencies
     QMAKE_CONFIG_DEPS = global global_private
+    QMAKE_LIBRARY_DEPS = $$eval(config.modules.global)
     !isEmpty($${currentConfig}.module) {
         for (d, $${currentConfig}.depends._KEYS_) {
             dep = $$replace($${currentConfig}.depends.$$d, -private$, _private)
-            dep *= $$replace(dep, _private$, )
+            gdep = $$replace(dep, _private$, )
+            dep *= $$gdep
             QMAKE_CONFIG_DEPS += $$dep
+            !isEqual(gdep, $$dep): \  # libraries are in the private module.
+                QMAKE_LIBRARY_DEPS += $$eval(config.modules.$$gdep)
         }
     }