Fix DS::Stream::readLine for files without a trailing newline

As is currently the case for some SDL files in the H'uru/Plasma repo.

streams.cpp

@@ -27,20 +27,19 @@ bool DS::Stream::readLine(void* buffer, size_t count)
     DS_ASSERT(count >= 1);
     char* outp = reinterpret_cast<char*>(buffer);
     char* endp = outp + count - 1;
-    bool eof = false;
 
     while (outp < endp) {
         ssize_t nread = readBytes(outp, 1);
         if (nread == 0) {
-            eof = true;
             break;
         }
         char c = *outp++;
         if (c == '\n')
             break;
     }
     *outp = 0;
-    return !eof;
+    // Signal EOF if the loop terminated without reading anything into the buffer.
+    return outp != buffer;
 }
 
 ST::string DS::Stream::readString(size_t length, DS::StringType format)