Implement generator support for extension fields (no encoder/decoder support yet)

tests/test_encode_extensions.c

@@ -0,0 +1,34 @@
+/* Tests extension fields.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <pb_encode.h>
+#include "alltypes.pb.h"
+#include "extensions.pb.h"
+
+int main(int argc, char **argv)
+{
+    AllTypes alltypes = {0};
+    int32_t extensionfield1 = 12345;
+    pb_extension_t ext1 = {&AllTypes_extensionfield1, &extensionfield1, NULL};
+    
+    alltypes.extensions = &ext1;
+    
+    uint8_t buffer[1024];
+    pb_ostream_t stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
+    
+    /* Now encode it and check if we succeeded. */
+    if (pb_encode(&stream, AllTypes_fields, &alltypes))
+    {
+        fwrite(buffer, 1, stream.bytes_written, stdout);
+        return 0; /* Success */
+    }
+    else
+    {
+        fprintf(stderr, "Encoding failed: %s\n", PB_GET_ERROR(&stream));
+        return 1; /* Failure */
+    }
+}
+