Remove libsync from apex_available allowlist

As libsync is NDK/LLNDK, it doesn't need to be aded to allowlist as
apex_available.

Bug: n/a
Test: m
Change-Id: I16cfb258a24bde4def428f1e6277f5d3c95c228c
diff --git a/apex/apex.go b/apex/apex.go
index 3f0f247..c1a4b40 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -2668,7 +2668,6 @@
 		"libbuildversion",
 		"libmath",
 		"libprocpartition",
-		"libsync",
 	}
 	//
 	// Module separator
@@ -2776,7 +2775,6 @@
 		"libstagefright_metadatautils",
 		"libstagefright_mpeg2extractor",
 		"libstagefright_mpeg2support",
-		"libsync",
 		"libui",
 		"libui_headers",
 		"libunwindstack",
@@ -2917,7 +2915,6 @@
 		"libstagefright_m4vh263dec",
 		"libstagefright_m4vh263enc",
 		"libstagefright_mp3dec",
-		"libsync",
 		"libui",
 		"libui_headers",
 		"libunwindstack",