impl: rename 'detail' to 'impl'

'impl' directory contains implementation-detail headers that are NOT
installed. 'detail' directory will be used for implementation-detail
headers that ARE installed.

refs #4782

Change-Id: I13428e032c93207753a6b856c693511c4fc3bbb8
diff --git a/wscript b/wscript
index 5f62e82..f5ec910 100644
--- a/wscript
+++ b/wscript
@@ -253,16 +253,16 @@
                                 excl=['ndn-cxx/**/*-osx.hpp',
                                       'ndn-cxx/**/*netlink*.hpp',
                                       'ndn-cxx/**/*-sqlite3.hpp',
-                                      'ndn-cxx/**/detail/**/*'])
+                                      'ndn-cxx/**/impl/**/*'])
 
     if bld.env['HAVE_OSX_FRAMEWORKS']:
-        headers += bld.path.ant_glob('ndn-cxx/**/*-osx.hpp', excl='ndn-cxx/**/detail/**/*')
+        headers += bld.path.ant_glob('ndn-cxx/**/*-osx.hpp', excl='ndn-cxx/**/impl/**/*')
 
     if bld.env['HAVE_NETLINK']:
-        headers += bld.path.ant_glob('ndn-cxx/**/*netlink*.hpp', excl='ndn-cxx/**/detail/**/*')
+        headers += bld.path.ant_glob('ndn-cxx/**/*netlink*.hpp', excl='ndn-cxx/**/impl/**/*')
 
     # In case we want to make it optional later
-    headers += bld.path.ant_glob('ndn-cxx/**/*-sqlite3.hpp', excl='ndn-cxx/**/detail/**/*')
+    headers += bld.path.ant_glob('ndn-cxx/**/*-sqlite3.hpp', excl='ndn-cxx/**/impl/**/*')
 
     bld.install_files(bld.env['INCLUDEDIR'], headers, relative_trick=True)