REORG: unix: move UNIX bind/server keywords from proto_uxst.c to cfgparse-unix.c

Let's finish the cleanup and get rid of all bind and server keywords
parsers from proto_uxst.c. They're now moved to cfgparse-unix.c. Now
proto_uxst.c is clean and only contains code related to binding and
connecting.
diff --git a/Makefile b/Makefile
index 854194e..2372af2 100644
--- a/Makefile
+++ b/Makefile
@@ -819,7 +819,8 @@
        src/ebsttree.o src/pipe.o src/hpack-enc.o src/fcgi.o                   \
        src/eb64tree.o src/dict.o src/shctx.o src/ebimtree.o                   \
        src/eb32tree.o src/ebtree.o src/dgram.o src/proto_udp.o                \
-       src/hpack-huff.o src/cfgparse-tcp.o src/base64.o src/version.o
+       src/hpack-huff.o src/cfgparse-tcp.o src/base64.o src/version.o         \
+       src/cfgparse-unix.o
 
 ifneq ($(TRACE),)
 OBJS += src/calltrace.o