Fix GCC build.

error: '__sdidinit' initialized and declared 'extern' [-Werror]

Change-Id: I97d9c174da6a99ca61b72572dfb4694813372a60

libc/bionic/ndk_cruft.cpp

@@ -287,11 +287,12 @@ extern "C" int getdtablesize() {
 }
 
 // A leaked BSD stdio implementation detail that's now a no-op.
-extern "C" void __sinit() {
+// (GCC doesn't like 'extern "C"' on a definition.)
+extern "C" {
+void __sinit() {}
+int __sdidinit = 1;
 }
 
-extern "C" int __sdidinit = 1;
-
 // Only used by ftime, which was removed from POSIX 2008.
 struct timeb {
   time_t          time;