oc-payload.cc: fix signed/unsigned char issues

When char == signed char, conversion to and from uint_8 fails in some
places. Started to happen recently in Ostro OS, perhaps because of a
compiler update.

The conversion of sid is straightforward.

OCSecurityPayload->securityData is less obvious: it is an uint_8
pointer, which seems to end up getting converted to a boolean instead
of a character string. The typecast unfortunately has to be done
inside the macro, reducing its type safety.

../src/structures/oc-payload.cc: In function 'v8::Local<v8::Object> js_OCDiscoveryPayload(OCDiscoveryPayload*)':
../src/structures/oc-payload.cc:240:30: error: invalid conversion from 'char*' to 'uint8_t* {aka unsigned char*}' [-fpermissive]
              js_SID(payload->sid));

In file included from ../src/structures/oc-payload.cc:18:0:
../src/structures/oc-payload.cc: In function 'v8::Local<v8::Object> js_OCSecurityPayload(OCSecurityPayload*)':
../src/structures/../common.h:63:45: error: 'Nan::imp::FactoryBase<v8::Boolean>::return_t {aka class v8::Local<v8::Boolean>}' has no member named 'ToLocalChecked'
              Nan::New((source)->memberName).ToLocalChecked());      \
                                             ^
../src/structures/oc-payload.cc:312:3: note: in expansion of macro 'SET_STRING_IF_NOT_NULL'
   SET_STRING_IF_NOT_NULL(returnValue, payload, securityData);

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>

src/common.h

@@ -60,7 +60,7 @@
 #define SET_STRING_IF_NOT_NULL(destination, source, memberName)     \
   if ((source)->memberName) {                                       \
     Nan::Set((destination), Nan::New(#memberName).ToLocalChecked(), \
-             Nan::New((source)->memberName).ToLocalChecked());      \
+             Nan::New(reinterpret_cast<const char *>((source)->memberName)).ToLocalChecked()); \
   }
 
 #define SET_VALUE_ON_OBJECT(destination, type, source, memberName) \

src/structures/oc-payload.cc

@@ -237,7 +237,7 @@ static Local<Object> js_OCDiscoveryPayload(OCDiscoveryPayload *payload) {
 
   if (payload->sid) {
     Nan::Set(returnValue, Nan::New("sid").ToLocalChecked(),
-             js_SID(payload->sid));
+             js_SID(reinterpret_cast<unsigned char *>(payload->sid)));
   }
 
   // Count the resources
@@ -266,7 +266,7 @@ static Local<Object> js_OCDevicePayload(OCDevicePayload *payload) {
 
   if (payload->sid) {
     Nan::Set(returnValue, Nan::New("sid").ToLocalChecked(),
-             js_SID(payload->sid));
+             js_SID(reinterpret_cast<unsigned char *>(payload->sid)));
   }
 
   SET_STRING_IF_NOT_NULL(returnValue, payload, deviceName);