qbs project files: Add library dir to rpaths for tools.

At least one tool uses libUtils, and others could very well do that too.

Change-Id: I4ddda966dc18ac05fc074a4e58df9f8c5dc09d44
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

qbs/imports/QtcTool.qbs

@@ -11,6 +11,10 @@ Application {
 
     property string toolInstallDir: project.ide_libexec_path
 
+    cpp.rpaths: qbs.targetOS.contains("osx")
+            ? ["@executable_path/../" + project.ide_library_path]
+            : ["$ORIGIN/../" + project.ide_library_path]
+
     Group {
         fileTagsFilter: product.type
         qbs.install: true