Fix wrong code generation if EN/ENO are used in FBD/LD/SFC

This problem appears for example here

--------
------- | MOVE |
| MOVE1 |------|EN ENO|
------- | |
| |
------- | | -----------
| 23 |------|IN OUT|---| LocalVar0 |
------- -------- -----------


--------
------- | MOVE |
| MOVE2 |------|EN ENO|
------- | |
| |
------- | | -----------
| 15 |------|IN OUT|---| LocalVar0 |
------- -------- -----------

Before wrong code was generated for this case:

MOVE6_OUT := MOVE(EN := move1, IN := 23, ENO => MOVE6_ENO);
LocalVar0 := MOVE6_OUT;
MOVE4_OUT := MOVE(EN := move2, IN := 15, ENO => MOVE4_ENO);
LocalVar0 := MOVE4_OUT;

With this patch now following code is generated:

MOVE6_OUT := MOVE(EN := move1, IN := 23, ENO => MOVE6_ENO);
IF MOVE6_ENO THEN
LocalVar0 := MOVE6_OUT;
END_IF;
MOVE4_OUT := MOVE(EN := move2, IN := 15, ENO => MOVE4_ENO);
IF MOVE4_ENO THEN
LocalVar0 := MOVE4_OUT;
END_IF;


See discussion here:
https://sourceforge.net/p/beremiz/mailman/message/36378805/

all:
	@echo "Please specify target 'source_list', 'template' or 'locales'"

template:
	@echo To generate translation template message.pot file:
	python mki18n.py -p --domain=Beremiz

locales:
	@echo "Generate .mo files for all languages:"
	python mki18n.py -m --moTarget=../locale --domain=Beremiz


source_list:
	echo @To "Generate list with source files: app.fil:"
	find .. -name "*.py" -exec grep -q '_(' {} ';' -print -o -name "*XSD*" -print -o -name "*.csv" -print | grep -v '/build/' | grep -v '/pyjs/' > app.fil
	echo "../plcopen/Additional_Function_Blocks.xml" >> app.fil
	echo "../plcopen/Standard_Function_Blocks.xml"   >> app.fil

.PHONY: all, template, locales, source_list