[Android] Roll the NDK to r11c.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 4c7dedc6a235cfb0f5327097985d25ea595daf84..30eda8155ed89faa6811e39b373b6749f15ee408 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -1726,6 +1726,8 @@
             # in the GYP files.
             'android_ndk_absolute_root%': '<!(cd <(DEPTH) && pwd -P)/third_party/android_tools/ndk/',
             'android_host_arch%': '<!(uname -m)',
+            # Version of the NDK. Used to ensure full rebuilds on NDK rolls.
+            'android_ndk_version%': 'r11c',
             # Android API-level of the SDK used for compilation.
             'android_sdk_version%': '23',
             'android_sdk_build_tools_version%': '23.0.1',
@@ -1749,6 +1751,7 @@
           # Copy conditionally-set variables out one scope.
           'android_ndk_root%': '<(android_ndk_root)',
           'android_ndk_absolute_root%': '<(android_ndk_absolute_root)',
+          'android_ndk_version%': '<(android_ndk_version)',
           'android_sdk_root%': '<(android_sdk_root)',
           'android_sdk_version%': '<(android_sdk_version)',
           'android_sdk_build_tools_version%': '<(android_sdk_build_tools_version)',
@@ -1820,6 +1823,7 @@
         'android_gdbserver%': '<(android_gdbserver)',
         'android_ndk_root%': '<(android_ndk_root)',
         'android_ndk_sysroot%': '<(android_ndk_sysroot)',
+        'android_ndk_version%': '<(android_ndk_version)',
         'android_sdk_root%': '<(android_sdk_root)',
         'android_sdk_version%': '<(android_sdk_version)',
         'android_toolchain%': '<(android_toolchain)',
@@ -4869,6 +4873,7 @@
               # The NDK has these things, but doesn't define the constants
               # to say that it does. Define them here instead.
               'HAVE_SYS_UIO_H',
+              'ANDROID_NDK_VERSION=<(android_ndk_version)',
             ],
             'ldflags!': [
               '-pthread',  # Not supported by Android toolchain.