beremiz

make attribute CFLAGS and LDFLAGS optional and add default empty value

Actually CFLAGS and LDFLAGS are not required and can be empty.
Without default empty value if target platform in project settings was
set to "Linux" CFLAGS and LDFLAGS was initialized with NoneType.
The result was broken build and it wasn't to save/load project with
such settings.

Traceback (most recent call last):
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 956, in _Build
if not builder.build() :
File "/home/developer/WorkData/PLC/beremiz/beremiz/targets/toolchain_gcc.py", line 96, in build
Builder_CFLAGS = ' '.join(self.getBuilderCFLAGS())
TypeError: sequence item 0: expected string, NoneType found
<?xml version='1.0' encoding='utf-8'?>
<CFile xmlns:xhtml="http://www.w3.org/1999/xhtml">
<includes>
<xhtml:p><![CDATA[
]]></xhtml:p>
</includes>
<variables>
<variable name="TestInput" type="SINT" initial="0"/>
<variable name="TestOutput" type="SINT"/>
</variables>
<globals>
<xhtml:p><![CDATA[
volatile long Lock=0;
volatile char PtoC=1,CtoP=2;
extern long AtomicCompareExchange(long*,long, long);
extern char *PLC_ID;
int Simple_C_Call(int val){
return val+1;
}
int Python_to_C_Call(char toC, char *fromC){
/* Code called by python should never touch to
variables modified by PLC thread directly
AtomicCompareExchange comes from
beremiz' runtime implementation */
int res = 0;
if(!AtomicCompareExchange((long*)&Lock, 0, 1)){
PtoC=toC;
*fromC=CtoP;
AtomicCompareExchange((long*)&Lock, 1, 0);
res=1;
}
printf("C code called by Python: toC %d fromC %d\n",toC,*fromC);
printf("PLC_ID id %s\n",PLC_ID);
return res;
}
int PLC_C_Call(char fromPLC, char *toPLC){
/* PLC also have to be realy carefull not to
conflict with asynchronous python access */
if(!AtomicCompareExchange((long*)&Lock, 0, 1)){
CtoP = fromPLC;
*toPLC = PtoC;
AtomicCompareExchange((long*)&Lock, 1, 0);
return 1;
}
return 0;
}
]]></xhtml:p>
</globals>
<initFunction>
<xhtml:p><![CDATA[
]]></xhtml:p>
</initFunction>
<cleanUpFunction>
<xhtml:p><![CDATA[
]]></xhtml:p>
</cleanUpFunction>
<retrieveFunction>
<xhtml:p><![CDATA[
]]></xhtml:p>
</retrieveFunction>
<publishFunction>
<xhtml:p><![CDATA[
if(!AtomicCompareExchange((long*)&Lock, 0, 1)){
TestInput = CtoP + PtoC + TestOutput;
AtomicCompareExchange((long*)&Lock, 1, 0);
}
]]></xhtml:p>
</publishFunction>
</CFile>