added dependency to xtend.lib

plugins/org.yakindu.sct.generator.c/META-INF/MANIFEST.MF

@@ -20,7 +20,8 @@ Require-Bundle: org.yakindu.sct.model.sexec,
  org.yakindu.sct.generator.genmodel;bundle-version="1.0.0",
  org.yakindu.base.types;bundle-version="1.0.0",
  org.eclipse.xtext.xbase.lib;bundle-version="2.3.0",
- org.eclipse.xtext.builder;bundle-version="2.3.0"
+ org.eclipse.xtext.builder;bundle-version="2.3.0",
+ org.eclipse.xtend.lib;bundle-version="2.3.0";resolution:=optional
 Bundle-RequiredExecutionEnvironment: J2SE-1.5
 Export-Package: org.yakindu.sct.generator.c,
  org.yakindu.sct.generator.c.features,