PROTOBUF_C_{NO_,}DEPRECATED -> PROTOBUF_C__{NO_,}DEPRECATED

these identifiers aren't intended for use by client code. add a double
underscore to indicate this.

protobuf-c/protobuf-c.h

@@ -45,12 +45,12 @@
 # define PROTOBUF_C__END_DECLS
 #endif
 
-#if !defined(PROTOBUF_C_NO_DEPRECATED)
+#if !defined(PROTOBUF_C__NO_DEPRECATED)
 # if (__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
-#  define PROTOBUF_C_DEPRECATED __attribute__((__deprecated__))
+#  define PROTOBUF_C__DEPRECATED __attribute__((__deprecated__))
 # endif
 #else
-# define PROTOBUF_C_DEPRECATED
+# define PROTOBUF_C__DEPRECATED
 #endif
 
 #if defined(_WIN32) && defined(PROTOBUF_C_USE_SHARED_LIB)

protoc-c/c_file.cc

@@ -225,8 +225,8 @@ void FileGenerator::GenerateSource(io::Printer* printer) {
     "/* Generated from: $filename$ */\n"
     "\n"
     "/* Do not generate deprecated warnings for self */\n"
-    "#ifndef PROTOBUF_C_NO_DEPRECATED\n"
-    "#define PROTOBUF_C_NO_DEPRECATED\n"
+    "#ifndef PROTOBUF_C__NO_DEPRECATED\n"
+    "#define PROTOBUF_C__NO_DEPRECATED\n"
     "#endif\n"
     "\n"
     "#include \"$basename$.pb-c.h\"\n",

protoc-c/c_helpers.cc

@@ -288,7 +288,7 @@ string FieldName(const FieldDescriptor* field) {
 
 string FieldDeprecated(const FieldDescriptor* field) {
   if (field->options().deprecated()) {
-    return " PROTOBUF_C_DEPRECATED";
+    return " PROTOBUF_C__DEPRECATED";
   }
   return "";
 }