libbase/liblog: set min_sdk_version

Modules contributing mainline modules (APK/APEX) should set
min_sdk_version as well as apex_available.

For now setting min_sdk_version doesn't change build outputs.
But build-time checks will be added soon.

Bug: 152655956
Test: m
Merged-In: If4ff1fbc31e5be3f5611a4713ae4032aba4ee5f2
Change-Id: If4ff1fbc31e5be3f5611a4713ae4032aba4ee5f2
(cherry picked from commit 3851f7e8361a84a15dffd7cbc08bee61d66f8fad)
diff --git a/base/Android.bp b/base/Android.bp
index 5b91078..0c78719 100644
--- a/base/Android.bp
+++ b/base/Android.bp
@@ -51,6 +51,7 @@
         "//apex_available:anyapex",
         "//apex_available:platform",
     ],
+    min_sdk_version: "29",
 }
 
 cc_defaults {
@@ -132,6 +133,7 @@
         "//apex_available:anyapex",
         "//apex_available:platform",
     ],
+    min_sdk_version: "29",
 }
 
 cc_library_static {