Remove execmod access to system_file and exec_type.

execmod is checked on attempts to make executable a file mapping
that has been modified.  Typically this indicates a text relocation
attempt.  As we do not ever allow this for any confined domain to
system_file or exec_type, we should not need it for unconfineddomain
either.

Change-Id: I8fdc858f836ae0d2aa56da2abd7797fba9c258b1
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

unconfined.te

@@ -61,10 +61,10 @@ allow unconfineddomain {
     -app_data_file
 }:{ dir lnk_file sock_file fifo_file } ~relabelto;
 allow unconfineddomain exec_type:dir r_dir_perms;
-allow unconfineddomain exec_type:file { r_file_perms execute execmod };
+allow unconfineddomain exec_type:file { r_file_perms execute };
 allow unconfineddomain exec_type:lnk_file r_file_perms;
 allow unconfineddomain system_file:dir r_dir_perms;
-allow unconfineddomain system_file:file { r_file_perms execute execmod };
+allow unconfineddomain system_file:file { r_file_perms execute };
 allow unconfineddomain system_file:lnk_file r_file_perms;
 allow unconfineddomain {
     fs_type