Address const issues in preparation for libcxx rebase.

Change-Id: I25a1e2946217049e9205589d6493e06362d2173b
diff --git a/cmds/installd/commands.cpp b/cmds/installd/commands.cpp
index 1b99582..5ecadef 100644
--- a/cmds/installd/commands.cpp
+++ b/cmds/installd/commands.cpp
@@ -1817,8 +1817,8 @@
 
 int calculate_oat_file_path(char path[PKG_PATH_MAX], const char *oat_dir, const char *apk_path,
         const char *instruction_set) {
-    char *file_name_start;
-    char *file_name_end;
+    const char *file_name_start;
+    const char *file_name_end;
 
     file_name_start = strrchr(apk_path, '/');
     if (file_name_start == NULL) {