Add support for cc_test.

This behaves slightly differently than it does in the make based build.

1. The make based build manually passes -DGTEST_OS_ANDROID (or
   whatever). gtest-port.h already has logic that does this, so it's a
   no-op.
2. Host libraries are named identically, rather than libgtest_host.

Change-Id: Ic40a1025c698611d202cb7c8ec45abd8fe130065
diff --git a/cmd/soong_build/main.go b/cmd/soong_build/main.go
index 5c954a9..d158f75 100644
--- a/cmd/soong_build/main.go
+++ b/cmd/soong_build/main.go
@@ -42,6 +42,7 @@
 	ctx.RegisterModuleType("cc_library", cc.NewCCLibrary)
 	ctx.RegisterModuleType("cc_object", cc.NewCCObject)
 	ctx.RegisterModuleType("cc_binary", cc.NewCCBinary)
+	ctx.RegisterModuleType("cc_test", cc.NewCCTest)
 
 	ctx.RegisterModuleType("toolchain_library", cc.NewToolchainLibrary)