Remove String16 header cruft.

-= forward declaration of imported class
-= empty extern decl

Bug: N/A
Test: N/A
Change-Id: I4eba90870f6d2e8d06fb49872cad51ca95da5ad9
diff --git a/libutils/include/utils/String16.h b/libutils/include/utils/String16.h
index adc3e7d..27eca0c 100644
--- a/libutils/include/utils/String16.h
+++ b/libutils/include/utils/String16.h
@@ -25,18 +25,10 @@
 
 // ---------------------------------------------------------------------------
 
-extern "C" {
-
-}
-
-// ---------------------------------------------------------------------------
-
 namespace android {
 
 // ---------------------------------------------------------------------------
 
-class String8;
-
 template <size_t N>
 class StaticString16;