Set FRAMEWORK_SEARCH_PATHS only when needed

We don't need to add $PODS_FRAMEWORK_BUILD_PATH, if there is no pod target, which should be build.
Fixes #3213.

lib/cocoapods/generator/xcconfig/aggregate_xcconfig.rb

@@ -60,10 +60,12 @@ module Pod
             header_search_paths = pod_targets.map { |target| "$PODS_FRAMEWORK_BUILD_PATH/#{target.product_name}/Headers" }
             build_settings = {
               'PODS_FRAMEWORK_BUILD_PATH' => target.configuration_build_dir,
-              'FRAMEWORK_SEARCH_PATHS' => '"$PODS_FRAMEWORK_BUILD_PATH"',
               # Make headers discoverable by `import "…"`
               'OTHER_CFLAGS' => '$(inherited) ' + XCConfigHelper.quote(header_search_paths, '-iquote'),
             }
+            if target.pod_targets.any?(&:should_build?)
+              build_settings['FRAMEWORK_SEARCH_PATHS'] = '"$PODS_FRAMEWORK_BUILD_PATH"'
+            end
             config.merge!(build_settings)
           else
             # Make headers discoverable from $PODS_ROOT/Headers directory

spec/unit/generator/xcconfig/aggregate_xcconfig_spec.rb

@@ -129,6 +129,16 @@ module Pod
 
           behaves_like 'AggregateXCConfig'
 
+          describe 'with a vendored-library pod' do
+            def spec
+              fixture_spec('monkey/monkey.podspec')
+            end
+
+            it 'does not add the framework build path to the xcconfig' do
+              @xcconfig.to_hash['FRAMEWORK_SEARCH_PATHS'].should.be.nil?
+            end
+          end
+
           it 'sets the PODS_FRAMEWORK_BUILD_PATH build variable' do
             @xcconfig.to_hash['PODS_FRAMEWORK_BUILD_PATH'].should == '$(BUILD_DIR)/$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME)/Pods'
           end