imap-send: build imap-send on Windows

Since the POSIX-specific tunneling code has been replaced
by the run-command API (and a compile-error has been
cleaned away), we can now enable imap-send on Windows
builds.
Signed-off-by: NErik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Makefile

@@ -350,6 +350,7 @@ EXTRA_PROGRAMS =
 PROGRAMS += $(EXTRA_PROGRAMS)
 PROGRAMS += git-fast-import$X
 PROGRAMS += git-hash-object$X
+PROGRAMS += git-imap-send$X
 PROGRAMS += git-index-pack$X
 PROGRAMS += git-merge-index$X
 PROGRAMS += git-merge-tree$X
@@ -1056,7 +1057,6 @@ EXTLIBS += -lz
 
 ifndef NO_POSIX_ONLY_PROGRAMS
 	PROGRAMS += git-daemon$X
-	PROGRAMS += git-imap-send$X
 endif
 ifndef NO_OPENSSL
 	OPENSSL_LIBSSL = -lssl