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

src/common/android/include/link.h

 // Copyright (c) 2012, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 12 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #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. */
+// 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.
+
+#define r_debug   __bionic_r_debug
+#define link_map  __bionic_link_map
+
 #include_next <link.h>
 
+#undef r_debug
+#undef link_map
+

[hush (inactive), 2016/07/19 18:52:36]

the block after line 48 won't be applied to 64 bit devices, which means r_debug
and link_map won't be defined

 // TODO(rmcilroy): Remove this file once the ndk is updated for other
 // architectures - crbug.com/358831
 #if !defined(__aarch64__) && !defined(__x86_64__) && \
     !(defined(__mips__) && _MIPS_SIM == _ABI64)
 
 #ifdef __cplusplus
 extern "C" {
 #endif  // __cplusplus
 
 struct r_debug {
@@ skipping 15 matching lines @@
   struct link_map* l_prev;
 };
 
 #ifdef __cplusplus
 }  // extern "C"
 #endif  // __cplusplus
 
 #endif  // !defined(__aarch64__) && !defined(__x86_64__)
 
 #endif /* GOOGLE_BREAKPAD_ANDROID_INCLUDE_LINK_H */