Allow installing qt interface files to fail

git-svn-id: https://openmodelica.org/svn/OpenModelica/trunk@24194 f25d12d1-65f4-0310-ae8a-bbce733d8d8e

Author: sjoelund

Compiler/boot/Makefile.common

@@ -131,4 +131,4 @@ install: $(GEN_DIR)omc$(EXE_EXT) install-interface
 endif
 
 install-interface:
-	cp -a $(GEN_DIR)OpenModelicaScriptingAPI.h ../Script/OpenModelicaScriptingAPIQt.cpp ../Script/OpenModelicaScriptingAPIQt.h $(OMHOME)/include/omc/scripting-API
+	-cp -a $(GEN_DIR)OpenModelicaScriptingAPI.h ../Script/OpenModelicaScriptingAPIQt.cpp ../Script/OpenModelicaScriptingAPIQt.h $(OMHOME)/include/omc/scripting-API