Add new file option php_namespace. (#3162)

* Add new file option php_namespace.

Use this option to change the namespace of php generated classes.
Default is empty. When this option is empty, the package name will be
used for determining the namespace.

* Uncomment commented tests

* Revert gdb test change

* Update csharp descriptor.

* Add test for empty php_namespace.

1 files changed, 8 insertions, 0 deletions

diff --git a/php/tests/proto/test_php_namespace.proto b/php/tests/proto/test_php_namespace.proto
new file mode 100644
index 00000000..713187b9
--- /dev/null
+++ b/php/tests/proto/test_php_namespace.proto
@@ -0,0 +1,8 @@
+syntax = "proto3";
+
+package foo;
+option php_namespace = "Php\\Test";
+
+message TestNamespace {
+  int32 a = 1;
+}