Add SkData::NewFromFD.

src/ports/SkOSFile_none.cpp

Index: src/ports/SkOSFile_none.cpp
===================================================================
--- src/ports/SkOSFile_none.cpp	(revision 9384)
+++ src/ports/SkOSFile_none.cpp	(working copy)
@@ -13,6 +13,10 @@
 
 void sk_fmunmap(const void* addr, size_t length) { }
 
+void* sk_fdmmap(int fd, size_t* size) {
+    return NULL;
+}
+
 void* sk_fmmap(SkFILE* f, size_t* size) {
     return NULL;
 }