Do not re-export _Unwind_XXX symbols.

The problem is that this library is getting _Unwind_XXX symbols from
libgcc.a for the arm targets, and then re-exporting them.

This is causing facebook to crash because a shared library is using
an undefined reference to an unwind symbol and then using the one
from libz.so, which is mixing an llvm unwinder with a gcc one.

Bug: 130267141

Test: facebook no longer crashes when starting up.
Change-Id: I1c2439f08375fbc630a49fdabcc50d22d461eb2b

Android.bp

@@ -47,7 +47,13 @@ cc_library {
 
             // TODO: This is to work around b/24465209. Remove after root cause is fixed
             pack_relocations: false,
-            ldflags: ["-Wl,--hash-style=both"],
+            ldflags: [
+                "-Wl,--hash-style=both",
+                // TODO: This works around b/130267141 to avoid re-exporting
+                // _Unwind_XXX symbols and needs to be removed when a
+                // global location for this can be found.
+                "-Wl,--exclude-libs,libgcc.a",
+            ],
         },
     },