[NaCl SDK] Change KernelProxy::GetCWD() to allocate path.

native_client_sdk/src/libraries/nacl_io/kernel_proxy.cc

Index: native_client_sdk/src/libraries/nacl_io/kernel_proxy.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/kernel_proxy.cc b/native_client_sdk/src/libraries/nacl_io/kernel_proxy.cc
index 672f51c30825aa1c9a8b4febf07f1047128e7b0c..e39302b03ff7a0947ff7bc96f64ffd693112070e 100644
--- a/native_client_sdk/src/libraries/nacl_io/kernel_proxy.cc
+++ b/native_client_sdk/src/libraries/nacl_io/kernel_proxy.cc
@@ -270,11 +270,6 @@ int KernelProxy::chdir(const char* path) {
 char* KernelProxy::getcwd(char* buf, size_t size) {
   std::string cwd = GetCWD();
 
-  if (size <= 0) {
-    errno = EINVAL;
-    return NULL;
-  }
-
   // If size is 0, allocate as much as we need.
   if (size == 0) {
     size = cwd.size() + 1;