Release 2.19.9

- [FEATURE] Add lsquic_stream_pwritev().  This function allows one to
  reduce the number of system calls required to read a file from disk
  by using lsquic_stream_pwritev() together with preadv(2).
- [BUGFIX] When stream is reset, it is writeable -- let user collect
  the error.
- [BUGFIX] Calculate correct conn flow control if reading ends early.
- [BUGFIX] Remove stream from read and write queues on internal
  shutdown.  This is a regression introduced in 2.19.7.
- [BUGFIX] Swapped arguments in IETF RESET_FRAME generation.
- Turn off mini conn history when compiling with Visual Studio; this
  allows the project to compile on Windows again.
- http_client: Add -3 flag to stop reading from streams early; code
  cleanup.
- Don't use -Werror.

include/lsquic.h

@@ -25,7 +25,7 @@ extern "C" {
 
 #define LSQUIC_MAJOR_VERSION 2
 #define LSQUIC_MINOR_VERSION 19
-#define LSQUIC_PATCH_VERSION 8
+#define LSQUIC_PATCH_VERSION 9
 
 /**
  * Engine flags:
@@ -1392,6 +1392,14 @@ lsquic_stream_write (lsquic_stream_t *s, const void *buf, size_t len);
 ssize_t
 lsquic_stream_writev (lsquic_stream_t *s, const struct iovec *vec, int count);
 
+/**
+ * Write to streams using a single call to a preadv-like function.
+ */
+ssize_t
+lsquic_stream_pwritev (lsquic_stream_t *s,
+    ssize_t (*preadv)(void *user_data, const struct iovec *iov, int iovcnt),
+    void *user_data, size_t n_to_write);
+
 /**
  * Used as argument to @ref lsquic_stream_writef()
  */