wscript: don't install detail/*.hpp

This commit also fixes include paths in face-impl.hpp.

refs #2266

Change-Id: I1bbca6cdb6ffaab134f52a383fe3efe36106244f
diff --git a/wscript b/wscript
index f7f3cf7..ddb2cf9 100644
--- a/wscript
+++ b/wscript
@@ -188,7 +188,7 @@
         bld.recurse("examples")
 
     headers = bld.path.ant_glob(['src/**/*.hpp'],
-                                 excl=['src/**/*-osx.hpp'])
+                                 excl=['src/**/*-osx.hpp', 'src/detail/*'])
     if bld.env['HAVE_OSX_SECURITY']:
         headers += bld.path.ant_glob('src/**/*-osx.hpp')