Replace security_context_t type

security_context_t has been marked as deprecated in libselinux from
version 3.2. Update to the `char*` type.

Bug: 190808996
Test: m
Change-Id: Icd8aa61b0f5981aeb0c605652e3fafd4670d78f3
diff --git a/cmds/cmd/cmd.cpp b/cmds/cmd/cmd.cpp
index be2c702..8f1c01a 100644
--- a/cmds/cmd/cmd.cpp
+++ b/cmds/cmd/cmd.cpp
@@ -52,7 +52,7 @@
 }
 
 struct SecurityContext_Delete {
-    void operator()(security_context_t p) const {
+    void operator()(char* p) const {
         freecon(p);
     }
 };
@@ -108,7 +108,7 @@
         }
         if (is_selinux_enabled() && seLinuxContext.size() > 0) {
             String8 seLinuxContext8(seLinuxContext);
-            security_context_t tmp = nullptr;
+            char* tmp = nullptr;
             getfilecon(fullPath.string(), &tmp);
             Unique_SecurityContext context(tmp);
             if (checkWrite) {