factor out hexadecimal constants.

Now we don't have to rely on the linker to de-duplicate
so many gHex[] constants.

Change-Id: Ia86d3a92648415afdb8d29499b4faded5ed05c7d
Reviewed-on: https://skia-review.googlesource.com/20180
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
diff --git a/src/core/SkUtils.h b/src/core/SkUtils.h
index 2ae6f87..832bdbd 100644
--- a/src/core/SkUtils.h
+++ b/src/core/SkUtils.h
@@ -107,4 +107,10 @@
     }
     return true;
 }
+
+namespace SkHexadecimalDigits {
+    extern const char gUpper[16];  // 0-9A-F
+    extern const char gLower[16];  // 0-9a-f
+}
+
 #endif