Reduce VABC memory usage

BlockExtentWriter caches data in memory up until get gets a complete
extent. For full OTAs, extents are chopped to 2MB chunks. But for
incremental OTAs, extents can be as large as single file size. We have
observed a single extent to span >100MB disk space on pixel. This incurs
significant memory overhead depending on layout of file system image.
To reduce VABC memory usage, bound memory cache by 1MB

Test: th
Bug: 279305177
Change-Id: I75dbdd60f7e9939fc0fcabe7510fc7ff800087be
diff --git a/common/utils.cc b/common/utils.cc
index 4c1365a..9723c8f 100644
--- a/common/utils.cc
+++ b/common/utils.cc
@@ -57,7 +57,9 @@
 
 #include "update_engine/common/constants.h"
 #include "update_engine/common/subprocess.h"
+#ifdef __ANDROID__
 #include "update_engine/common/platform_constants.h"
+#endif
 #include "update_engine/payload_consumer/file_descriptor.h"
 
 using base::Time;