Add file access modes to sk_exists.

src/ports/SkOSFile_stdio.cpp

Index: src/ports/SkOSFile_stdio.cpp
diff --git a/src/ports/SkOSFile_stdio.cpp b/src/ports/SkOSFile_stdio.cpp
index ad26c807c79e45a6b5e30b367e7eb4c6b62d551e..d63462549c33d11b80a42690d8f9f79f17b3dcc4 100644
--- a/src/ports/SkOSFile_stdio.cpp
+++ b/src/ports/SkOSFile_stdio.cpp
@@ -15,8 +15,6 @@
 #ifdef _WIN32
 #include <direct.h>
 #include <io.h>
-#else
-#include <unistd.h>
 #endif
 
 SkFILE* sk_fopen(const char path[], SkFILE_Flags flags) {
@@ -123,14 +121,6 @@ void sk_fclose(SkFILE* f) {
     ::fclose((FILE*)f);
 }
 
-bool sk_exists(const char *path) {
-#ifdef _WIN32
-    return (0 == _access(path, 0));
-#else
-    return (0 == access(path, 0));
-#endif
-}
-
 bool sk_isdir(const char *path) {
     struct stat status;
     if (0 != stat(path, &status)) {