Update version number in generated files.

src/google/protobuf/compiler/plugin.pb.h

@@ -13,7 +13,7 @@
 #error incompatible with your Protocol Buffer headers.  Please update
 #error your headers.
 #endif
-#if 2006000 < GOOGLE_PROTOBUF_MIN_PROTOC_VERSION
+#if 2006001 < GOOGLE_PROTOBUF_MIN_PROTOC_VERSION
 #error This file was generated by an older version of protoc which is
 #error incompatible with your Protocol Buffer headers.  Please
 #error regenerate this file with a newer version of protoc.

src/google/protobuf/descriptor.pb.h

@@ -13,7 +13,7 @@
 #error incompatible with your Protocol Buffer headers.  Please update
 #error your headers.
 #endif
-#if 2006000 < GOOGLE_PROTOBUF_MIN_PROTOC_VERSION
+#if 2006001 < GOOGLE_PROTOBUF_MIN_PROTOC_VERSION
 #error This file was generated by an older version of protoc which is
 #error incompatible with your Protocol Buffer headers.  Please
 #error regenerate this file with a newer version of protoc.