Merge "Flag an error on empty rust module srcs" am: 6ec96b8102 am: 2e2fb66ecc am: fdf99b1a08 am: a10377c7fd

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1852788

Change-Id: I5a49c3b31bd2ca254ecfd77c24f12a005dffc88b
diff --git a/android/variable.go b/android/variable.go
index 4a82f23..e7641af 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -116,6 +116,8 @@
 			Shared_libs       []string
 
 			Cmdline []string
+			Srcs         []string
+			Exclude_srcs []string
 		}
 
 		// eng is true for -eng builds, and can be used to turn on additionaly heavyweight debugging