Deprecate depfile in gensrcs

All existing gensrsc modulePartners who use the property can use BUILD_BROKEN_DEP_FILE to bypass the error

Test: CI
Bug: 179452413
Fix: 179452413
Change-Id: I7cd39484b43eba693d79188b9a374f192198f90f

android/variable.go

@@ -428,6 +428,7 @@ type productVariables struct {
 
 	ShippingApiLevel *string `json:",omitempty"`
 
+	BuildBrokenDepfile                 *bool    `json:",omitempty"`
 	BuildBrokenEnforceSyspropOwner     bool     `json:",omitempty"`
 	BuildBrokenTrebleSyspropNeverallow bool     `json:",omitempty"`
 	BuildBrokenVendorPropertyNamespace bool     `json:",omitempty"`