Upgrade to 0.7.1

Test: build, TH
Change-Id: I3cb2c39b931e2b5c5b1a0bf775c6185c0e521da8
diff --git a/grpc/.gitmodules b/grpc/.gitmodules
index 9097319..781cfac 100644
--- a/grpc/.gitmodules
+++ b/grpc/.gitmodules
@@ -8,7 +8,6 @@
 [submodule "third_party/protobuf"]
 	path = third_party/protobuf
 	url = https://github.com/google/protobuf.git
-	branch = 3.0.x
 [submodule "third_party/gflags"]
 	path = third_party/gflags
 	url = https://github.com/gflags/gflags.git
@@ -21,6 +20,9 @@
 [submodule "third_party/boringssl-with-bazel"]
 	path = third_party/boringssl-with-bazel
 	url = https://github.com/google/boringssl.git
+[submodule "third_party/re2"]
+	path = third_party/re2
+	url = https://github.com/google/re2.git
 [submodule "third_party/cares/cares"]
 	path = third_party/cares/cares
 	url = https://github.com/c-ares/c-ares.git