AAPT2 statically link libz on Windows builds

Change-Id: I2abf47273173c470c04e00a54aa619fe1ce0e745
diff --git a/tools/aapt2/Android.mk b/tools/aapt2/Android.mk
index e61fd29..9cea176 100644
--- a/tools/aapt2/Android.mk
+++ b/tools/aapt2/Android.mk
@@ -70,8 +70,8 @@
 	XmlFlattener_test.cpp
 
 cIncludes :=
+hostLdLibs :=
 
-hostLdLibs := -lz
 hostStaticLibs := \
 	libandroidfw \
 	libutils \
@@ -80,6 +80,12 @@
 	libexpat \
 	libziparchive-host
 
+ifneq ($(strip $(USE_MINGW)),)
+	hostStaticLibs += libz
+else
+	hostLdLibs += -lz
+endif
+
 cFlags := -Wall -Werror -Wno-unused-parameter -UNDEBUG
 cppFlags := -std=c++11 -Wno-missing-field-initializers