Move proxy-related source files into a subdirectory.

There are quite a few of them already, and I'm about to make another
one, so let's start with a bit of tidying up.

The CMake build organisation is unchanged: I haven't put the proxy
object files into a separate library, just moved the locations of the
source files. (Organising proxying as a library would be tricky
anyway, because of the various overrides for tools that want to avoid
cryptography.)

windows/CMakeLists.txt

@@ -111,8 +111,8 @@ add_executable(puttytel
   ${CMAKE_SOURCE_DIR}/be_nos_s.c
   ${CMAKE_SOURCE_DIR}/nogss.c
   ${CMAKE_SOURCE_DIR}/norand.c
-  ${CMAKE_SOURCE_DIR}/nocproxy.c
-  ${CMAKE_SOURCE_DIR}/nosshproxy.c
+  ${CMAKE_SOURCE_DIR}/proxy/nocproxy.c
+  ${CMAKE_SOURCE_DIR}/proxy/nosshproxy.c
   puttytel.rc)
 add_dependencies(puttytel generated_licence_h)
 target_link_libraries(puttytel
@@ -152,7 +152,7 @@ if(HAVE_CONPTY)
     be_conpty.c
     ${CMAKE_SOURCE_DIR}/nogss.c
     ${CMAKE_SOURCE_DIR}/norand.c
-    ${CMAKE_SOURCE_DIR}/nosshproxy.c
+    ${CMAKE_SOURCE_DIR}/proxy/nosshproxy.c
     pterm.rc)
   add_dependencies(pterm generated_licence_h)
   target_link_libraries(pterm

windows/local-proxy.c

@@ -10,7 +10,7 @@
 #include "tree234.h"
 #include "putty.h"
 #include "network.h"
-#include "proxy.h"
+#include "proxy/proxy.h"
 
 Socket *platform_new_connection(SockAddr *addr, const char *hostname,
                                 int port, bool privport,

windows/named-pipe-client.c

@@ -8,7 +8,7 @@
 #include "tree234.h"
 #include "putty.h"
 #include "network.h"
-#include "proxy.h"
+#include "proxy/proxy.h"
 #include "ssh.h"
 
 #include "security-api.h"

windows/named-pipe-server.c

@@ -8,7 +8,7 @@
 #include "tree234.h"
 #include "putty.h"
 #include "network.h"
-#include "proxy.h"
+#include "proxy/proxy.h"
 #include "ssh.h"
 
 #include "security-api.h"

windows/sharing.c

@@ -8,7 +8,7 @@
 #include "tree234.h"
 #include "putty.h"
 #include "network.h"
-#include "proxy.h"
+#include "proxy/proxy.h"
 #include "ssh.h"
 
 #include "cryptoapi.h"