Move java.sdkSpec to the android package

... in preparation for making the handling of sdk versions consistent
across java and cc modules.

Bug: 175678607
Test: m
Change-Id: I598f0454bce9b7320621022115412fbe97403945
diff --git a/apex/builder.go b/apex/builder.go
index da800d4..2df380b 100644
--- a/apex/builder.go
+++ b/apex/builder.go
@@ -950,6 +950,10 @@
 				if v := m.MinSdkVersion(); v != "" {
 					toMinSdkVersion = v
 				}
+			} else if m, ok := to.(interface{ MinSdkVersionString() string }); ok {
+				if v := m.MinSdkVersionString(); v != "" {
+					toMinSdkVersion = v
+				}
 			}
 
 			depInfos[to.Name()] = android.ApexModuleDepInfo{