[libsigc++2] Remove the (generated) sigc++/retype.h header.

[Murray Cumming <murrayc src gnome org>]

commit 0b8d2f769deec397d5441c6429c4a2544d9f1a95
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Aug 12 10:39:51 2015 +0200

    Remove the (generated) sigc++/retype.h header.
    
    Because it now contains no API.
    See https://bugzilla.gnome.org/show_bug.cgi?id=752560#c6
    
    sigc++/macros/retype_h.m4 did define some m4 macros but these were
    not actually used. The generated sigc++/retype.h file did not
    include sigc++/adaptors/retype.h so it did not exist as a convenience.

 sigc++/filelist.am        |    4 +-
 sigc++/macros/retype.h.m4 |   75 ---------------------------------------------
 2 files changed, 2 insertions(+), 77 deletions(-)
---
diff --git a/sigc++/filelist.am b/sigc++/filelist.am
index dd09d22..8486b8e 100644
--- a/sigc++/filelist.am
+++ b/sigc++/filelist.am
@@ -17,11 +17,11 @@
 
 # Base (./)
 base_m4 = template.macros.m4 signal.h.m4 slot.h.m4 \
-         hide.h.m4 retype.h.m4 \
+         hide.h.m4 \
          limit_reference.h.m4
 base_built_cc =
 base_built_h = signal.h slot.h \
-              hide.h retype.h limit_reference.h
+              hide.h limit_reference.h
 
 # Functors (functors/)
 functors_m4 = functor_trait.h.m4 slot.h.m4 ptr_fun.h.m4 mem_fun.h.m4