# HG changeset patch
# User Andrey Skvortsov <andrej.skvortzov@gmail.com>
# Date 1460995011 -10800
# Node ID 69fe0b81e9519f20272dcd3e0583e7a973559821
# Parent  270dba8bf87b1fa9ec13135ca96679b8226ecb64
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

diff -r 270dba8bf87b -r 69fe0b81e951 targets/XSD_toolchain_gcc
--- a/targets/XSD_toolchain_gcc	Mon Apr 18 18:51:59 2016 +0300
+++ b/targets/XSD_toolchain_gcc	Mon Apr 18 18:56:51 2016 +0300
@@ -1,5 +1,5 @@
 
           <xsd:attribute name="Compiler" type="xsd:string" use="optional" default="gcc"/>
-          <xsd:attribute name="CFLAGS" type="xsd:string" use="required"/>
+          <xsd:attribute name="CFLAGS" type="xsd:string" use="optional" default=""/>
           <xsd:attribute name="Linker" type="xsd:string" use="optional" default="gcc"/>
-          <xsd:attribute name="LDFLAGS" type="xsd:string" use="required"/>
+          <xsd:attribute name="LDFLAGS" type="xsd:string" use="optional" default=""/>