Bug 1428182 - 9. Apply Skia upstream commit to support NDK r16; r=lsalzman

Apply Skia upstream commit 592c225b03ca677a1217eabdbc38eede6afcdb14 to
support building with NDK r16.

MozReview-Commit-ID: B6popOoPTni

--HG--
extra : rebase_source : bfdf40f6542c4c9dae0ef19379fb650107cf8077

gfx/skia/skia/src/core/SkCpu.cpp

@@ -85,8 +85,10 @@
         return features;
     }
 
-#elif defined(SK_CPU_ARM32) && __has_include(<asm/hwcap.h>) && __has_include(<sys/auxv.h>)
-    // asm/hwcap.h and sys/auxv.h won't be present on NDK builds before API v21.
+#elif defined(SK_CPU_ARM32) && __has_include(<sys/auxv.h>) && \
+    (!defined(__ANDROID_API__) || __ANDROID_API__ >= 18)
+    // sys/auxv.h will always be present in the Android NDK due to unified
+    //headers, but getauxval is only defined for API >= 18.
     #include <asm/hwcap.h>
     #include <sys/auxv.h>