Extend python<->PLC global variable description "GlobalDesc" to support Initial value setting.

Rebased from dporopat change "add initial value to runtime.py file", which means :
- GlobalDesc is used by some customized beremiz python runtime
- Those runtimes need to know what is initial value of these special variables

#! gmake

yml := ../../yml2
ysl2files := $(wildcard *.ysl2)
xsltfiles := $(patsubst %.ysl2, %.xslt, $(ysl2files))

all:$(xsltfiles)

%.xslt: %.ysl2
	$(yml)/yml2c -I $(yml) $< -o $@.tmp
	xmlstarlet fo $@.tmp > $@
	rm $@.tmp
	
clean:
	rm -f $(xsltfiles)