php: drop php client

Issue vitessio#3230
Now that we support mysql protocol, there's no need to support
a custom PHP client any more.

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "php/pdo"]
-	path = php/pdo
-	url = https://github.com/pixelfederation/vitess-php-pdo.git

Makefile

@@ -18,7 +18,7 @@ MAKEFLAGS = -s
 # Since we are not using this Makefile for compilation, limiting parallelism will not increase build time.
 .NOTPARALLEL:
 
-.PHONY: all build build_web test clean unit_test unit_test_cover unit_test_race integration_test proto proto_banner site_test site_integration_test docker_bootstrap docker_test docker_unit_test java_test php_test reshard_tests
+.PHONY: all build build_web test clean unit_test unit_test_cover unit_test_race integration_test proto proto_banner site_test site_integration_test docker_bootstrap docker_test docker_unit_test java_test reshard_tests
 
 all: build
 
@@ -113,10 +113,6 @@ java_test:
 	go install ./go/cmd/vtgateclienttest ./go/cmd/vtcombo
 	mvn -f java/pom.xml clean verify
 
-php_test:
-	go install ./go/cmd/vtgateclienttest
-	phpunit php/tests
-
 # TODO(mberlin): Remove the manual copy once govendor supports a way to
 # install vendor'd programs: https://github.com/kardianos/govendor/issues/117
 install_protoc-gen-go:
@@ -167,15 +163,6 @@ $(PROTO_GO_TEMPS): go/vt/.proto.tmp/%.pb.go: proto/%.proto
 	$(PROTOC_DIR)/protoc -Iproto $< --go_out=plugins=grpc:go/vt/.proto.tmp
 	sed -i -e 's,import \([a-z0-9_]*\) ".",import \1 "github.com/youtube/vitess/go/vt/proto/\1",g' $@
 
-# Generate the PHP proto files in a Docker container, and copy them back.
-php_proto:
-	docker run -ti --name=vitess_php-proto -v $$PWD/proto:/in vitess/bootstrap:common bash -c 'cd $$VTTOP && mkdir -p proto && cp -R /in/* proto/ && tools/proto-gen-php.sh'
-	docker cp vitess_php-proto:/vt/src/github.com/youtube/vitess/php/src/descriptor.php php/src/
-	docker cp vitess_php-proto:/vt/src/github.com/youtube/vitess/php/src/php.php php/src/
-	rm -r php/src/Vitess/Proto/*
-	docker cp vitess_php-proto:/vt/src/github.com/youtube/vitess/php/src/Vitess/Proto/. php/src/Vitess/Proto/
-	docker rm vitess_php-proto
-
 # Helper targets for building Docker images.
 # Please read docker/README.md to understand the different available images.