Don't define |r_debug| and |link_map| on Android releases 21 and later

src/common/android/include/link.h

Index: src/common/android/include/link.h
diff --git a/src/common/android/include/link.h b/src/common/android/include/link.h
index e7ff8e2d8702b0037921b50c99b94f02758f6e2a..d923a168765664f4f537250bad6e748a6cb75f93 100644
--- a/src/common/android/include/link.h
+++ b/src/common/android/include/link.h
@@ -30,15 +30,30 @@
 #ifndef GOOGLE_BREAKPAD_ANDROID_INCLUDE_LINK_H
 #define GOOGLE_BREAKPAD_ANDROID_INCLUDE_LINK_H
 
-/* Android doesn't provide all the data-structures required in its <link.h>.
-   Provide custom version here. */
-#include_next <link.h>
-
 // TODO(rmcilroy): Remove this file once the ndk is updated for other
 // architectures - crbug.com/358831
+
+// Android doesn't provide all the data-structures required in
+// its <link.h> before release 21. Provide custom version here and
+// rename Bionic-provided structures to avoid conflicts.
+
+#if !defined(__aarch64__) && !defined(__x86_64__) && \
+    !(defined(__mips__) && _MIPS_SIM == _ABI64)
+
+#define r_debug   __bionic_r_debug
+#define link_map  __bionic_link_map
+
+#endif  // !defined(__aarch64__) && !defined(__x86_64__) &&
+        // !(defined(__mips__) && _MIPS_SIM == _ABI64)
+
+#include_next <link.h>
+
 #if !defined(__aarch64__) && !defined(__x86_64__) && \
     !(defined(__mips__) && _MIPS_SIM == _ABI64)
 
+#undef r_debug
+#undef link_map
+
 #ifdef __cplusplus
 extern "C" {
 #endif  // __cplusplus
@@ -66,6 +81,7 @@ struct link_map {
 }  // extern "C"
 #endif  // __cplusplus
 
-#endif  // !defined(__aarch64__) && !defined(__x86_64__)
+#endif  // !defined(__aarch64__) && !defined(__x86_64__) &&
+        // !(defined(__mips__) && _MIPS_SIM == _ABI64)
 
 #endif /* GOOGLE_BREAKPAD_ANDROID_INCLUDE_LINK_H */