MEDIUM: connections: Introduce a handshake pseudo-XPRT.

Add a new XPRT that is used when using non-SSL handshakes, such as proxy
protocol or Netscaler, instead of taking care of it in conn_fd_handler().
This XPRT is installed when any of those is used, and it removes itself once
the handshake is done.
This should allow us to remove the distinction between CO_FL_SOCK* and
CO_FL_XPRT*.
diff --git a/Makefile b/Makefile
index 6695974..5d83867 100644
--- a/Makefile
+++ b/Makefile
@@ -788,7 +788,8 @@
        src/xxhash.o src/hpack-enc.o src/h2.o src/freq_ctr.o src/lru.o         \
        src/protocol.o src/arg.o src/hpack-huff.o src/hdr_idx.o src/base64.o   \
        src/hash.o src/mailers.o src/activity.o src/http_msg.o src/version.o   \
-       src/mworker.o src/mworker-prog.o src/debug.o src/wdt.o src/dict.o
+       src/mworker.o src/mworker-prog.o src/debug.o src/wdt.o src/dict.o      \
+       src/xprt_handshake.o
 
 EBTREE_OBJS = $(EBTREE_DIR)/ebtree.o $(EBTREE_DIR)/eb32sctree.o \
               $(EBTREE_DIR)/eb32tree.o $(EBTREE_DIR)/eb64tree.o \