Enable goma in soong

Pass the USE_GOMA flag to soong, and export the CC_WRAPPER environment
variable after adding gomacc to it.

Bug: 31142427
Change-Id: I6de698a40817c0615b03fa17bd27075465d79ffd
diff --git a/core/config.mk b/core/config.mk
index fb05897..a2d5e3f 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -284,6 +284,9 @@
 include $(BUILD_SYSTEM)/ccache.mk
 include $(BUILD_SYSTEM)/goma.mk
 
+export CC_WRAPPER
+export CXX_WRAPPER
+
 ifdef TARGET_PREFER_32_BIT
 TARGET_PREFER_32_BIT_APPS := true
 TARGET_PREFER_32_BIT_EXECUTABLES := true
diff --git a/core/ninja.mk b/core/ninja.mk
index 533553e..04efcc1 100644
--- a/core/ninja.mk
+++ b/core/ninja.mk
@@ -131,8 +131,8 @@
 
 $(COMBINED_BUILD_NINJA): $(KATI_BUILD_NINJA)
 	$(hide) echo "builddir = $(OUT_DIR)" > $(COMBINED_BUILD_NINJA)
-	$(hide) echo "subninja $(SOONG_BUILD_NINJA)" >> $(COMBINED_BUILD_NINJA)
-	$(hide) echo "subninja $(KATI_BUILD_NINJA)" >> $(COMBINED_BUILD_NINJA)
+	$(hide) echo "include $(KATI_BUILD_NINJA)" >> $(COMBINED_BUILD_NINJA)
+	$(hide) echo "include $(SOONG_BUILD_NINJA)" >> $(COMBINED_BUILD_NINJA)
 
 $(sort $(DEFAULT_GOAL) $(ANDROID_GOALS)) : ninja_wrapper
 	@#empty
diff --git a/core/soong.mk b/core/soong.mk
index 80dcefd..29a91e2 100644
--- a/core/soong.mk
+++ b/core/soong.mk
@@ -54,6 +54,7 @@
 	echo '    "Binder32bit": $(if $(BINDER32BIT),true,false),'; \
 	echo '    "DevicePrefer32BitExecutables": $(if $(filter true,$(TARGET_PREFER_32_BIT_EXECUTABLES)),true,false),'; \
 	echo '    "HostPrefer32BitExecutables": $(if $(filter true,$(HOST_PREFER_32_BIT)),true,false),'; \
+	echo '    "UseGoma": $(if $(filter-out false,$(USE_GOMA)),true,false),'; \
 	echo ''; \
 	echo '    "DeviceName": "$(TARGET_DEVICE)",'; \
 	echo '    "DeviceArch": "$(TARGET_ARCH)",'; \