Fix amalgamated build

Move libperfetto_client_experimental one level up
and point gen_amalgamated to it.

Test: manual. Works, see https://github.com/primiano/perfetto-sdk
Bug: 132678367
Change-Id: If542ffdf9eb303334eddb6f7b4eabca53f7c8459
diff --git a/tools/gen_amalgamated b/tools/gen_amalgamated
index 77bc463..bfc9f97 100755
--- a/tools/gen_amalgamated
+++ b/tools/gen_amalgamated
@@ -31,7 +31,10 @@
 
 # Default targets to include in the result.
 default_targets = [
-    '//:libperfetto',
+    '//:libperfetto_client_experimental',
+    "//protos/perfetto/trace:zero",
+    "//protos/perfetto/config:zero",
+    "//protos/perfetto/common:zero",
 ]
 
 # Arguments for the GN output directory (unless overridden from the command