Avoid including link.h.

It's not available on Android. We only use this header to find out if _DYNAMIC
is present; declaring it "extern void*" does the trick.

llvm-svn: 153431

compiler-rt/lib/asan/asan_linux.cc

@@ -25,7 +25,6 @@
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <fcntl.h>
-#include <link.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -36,6 +35,8 @@
 #include <sys/ucontext.h>
 #endif
 
+extern "C" void* _DYNAMIC;
+
 namespace __asan {
 
 void *AsanDoesNotSupportStaticLinkage() {