MINOR: h3: Add a statistics module for h3

Add ->inc_err_cnt new callback to qcc_app_ops struct which can
be called from xprt to increment the application level error code counters.
It take the application context as first parameter to be generic and support
new QUIC applications to come.
Add h3_stats.c module with counters for all the frame types and error codes.
diff --git a/Makefile b/Makefile
index 59b383c..7957027 100644
--- a/Makefile
+++ b/Makefile
@@ -637,7 +637,7 @@
                 src/quic_frame.o src/quic_cc.o src/quic_cc_newreno.o src/mux_quic.o \
                 src/cbuf.o src/qpack-dec.o src/qpack-tbl.o src/h3.o src/qpack-enc.o \
                 src/hq_interop.o src/cfgparse-quic.o src/quic_loss.o \
-                src/quic_tp.o src/quic_stream.o src/quic_stats.o
+                src/quic_tp.o src/quic_stream.o src/quic_stats.o src/h3_stats.o
 endif
 
 ifneq ($(USE_LUA),)