Limit warning message to de-clutter bench output logs

src/core/SkTypeface.cpp

Index: src/core/SkTypeface.cpp
===================================================================
--- src/core/SkTypeface.cpp	(revision 11507)
+++ src/core/SkTypeface.cpp	(working copy)
@@ -253,7 +253,12 @@
 
 int SkTypeface::onCharsToGlyphs(const void* chars, Encoding encoding,
                                 uint16_t glyphs[], int glyphCount) const {
-    SkDebugf("onCharsToGlyphs unimplemented\n");
+    static bool printed = false;
+    if (!printed) {
+        // Only want to see this message once
+        SkDebugf("\n *** onCharsToGlyphs unimplemented ***\n");
+        printed = true;
+    }
     if (glyphs && glyphCount > 0) {
         sk_bzero(glyphs, glyphCount * sizeof(glyphs[0]));
     }