Add a test for getdelim(3) on a directory.

Apparently uClibc has a bug here. We don't, but let's keep it that way.

Bug: http://landley.net/notes.html#21-03-2015
Change-Id: If406df963db9bee47921d7a1c116ebcab08d96bf

tests/stdio_test.cpp

@@ -151,6 +151,15 @@ TEST(stdio, getdelim_invalid) {
   fclose(fp);
 }
 
+TEST(stdio, getdelim_directory) {
+  FILE* fp = fopen("/proc", "r");
+  ASSERT_TRUE(fp != NULL);
+  char* word_read;
+  size_t allocated_length;
+  ASSERT_EQ(-1, getdelim(&word_read, &allocated_length, ' ', fp));
+  fclose(fp);
+}
+
 TEST(stdio, getline) {
   FILE* fp = tmpfile();
   ASSERT_TRUE(fp != NULL);