Support paths for vintf_fragments from Soong.

The property vintf_fragments accepts paths and references to other
modules; however, none of that is passed onto make, resulting in errors
if a non-local path is used.

Test: m
Bug: 184567830
Change-Id: If3b56ea8eec3b95b3a310b58bffd045cedd8ee52
diff --git a/android/androidmk.go b/android/androidmk.go
index 618e4be..590eceb 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -550,7 +550,9 @@
 		if !amod.InRamdisk() && !amod.InVendorRamdisk() {
 			a.AddPaths("LOCAL_FULL_INIT_RC", amod.initRcPaths)
 		}
-		a.AddStrings("LOCAL_VINTF_FRAGMENTS", amod.commonProperties.Vintf_fragments...)
+		if len(amod.vintfFragmentsPaths) > 0 {
+			a.AddPaths("LOCAL_FULL_VINTF_FRAGMENTS", amod.vintfFragmentsPaths)
+		}
 		a.SetBoolIfTrue("LOCAL_PROPRIETARY_MODULE", Bool(amod.commonProperties.Proprietary))
 		if Bool(amod.commonProperties.Vendor) || Bool(amod.commonProperties.Soc_specific) {
 			a.SetString("LOCAL_VENDOR_MODULE", "true")