[seahorse] Remove HACKING and INSTALL files.

[Niels De Graef <nielsdg src gnome org>]

commit 73dfbe51440bd16989da4c3e3ef36d9a4f6e54fa
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Thu Nov 9 21:24:45 2017 +0100

    Remove HACKING and INSTALL files.
    
    * HACKING is really outdated.
    * INSTALL is auto-generated and only describes autotools.

 HACKING     |  112 ----------------------------
 INSTALL     |  236 -----------------------------------------------------------
 Makefile.am |    2 -
 3 files changed, 0 insertions(+), 350 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 8543fe8..29deb23 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -16,8 +16,6 @@ EXTRA_DIST = \
     ChangeLog.pre-auto \
     ChangeLog.pre-1.0 \
     ChangeLog.pre-0.6 \
-    HACKING \
-    INSTALL \
     NEWS \
     README.md \
     THANKS