Add cache validation to ensure the validity

Create cache identity from GL_VERSION and store in ShaderCache.
In the next time ShaderCache is restored from disk, compare the
cache identity to ensure its validity. If GL_VERSION changes in
between, flush out entire FileBlobCache and start from an empty
one.

Bug: b/71800782
Test: Wrote a new unit test to save and restore ShaderCache
Test: hwui_unit_tests
Change-Id: Ie573dc4f18733eee090725be30445d879765231b
diff --git a/libs/hwui/Android.bp b/libs/hwui/Android.bp
index d582983..edce305 100644
--- a/libs/hwui/Android.bp
+++ b/libs/hwui/Android.bp
@@ -72,6 +72,7 @@
         "libft2",
         "libminikin",
         "libandroidfw",
+        "libcrypto",
     ],
     static_libs: [
         "libEGL_blobCache",