Add selabel_get_digests_all_partial_matches binary

Add build rule for selabel_get_digests_all_partial_matches. It is not
included by default in the system image, but can be useful to debug
the computation of security.sehash.

Bug: 317296680
Test: adb remount; adb push selabel_get_digests_all_partial_matches
  /system/bin; selabel_get_digests_all_partial_matches -r /data/data
Change-Id: I2b7e8d994f15539849d69ded5695293c4f2cf8b2

libselinux/Android.bp

@@ -222,6 +222,18 @@ cc_binary_host {
     stl: "",
 }
 
+cc_binary {
+    name: "selabel_get_digests_all_partial_matches",
+    defaults: ["libselinux_defaults"],
+    srcs: ["utils/selabel_get_digests_all_partial_matches.c"],
+
+    static_libs: [
+        "libselinux",
+    ],
+
+    stl: "",
+}
+
 rust_bindgen {
     name: "libselinux_bindgen",
     wrapper_src: "rust/selinux.h",

libselinux/utils/selabel_get_digests_all_partial_matches.c

@@ -5,6 +5,7 @@
 #include <errno.h>
 #include <stdbool.h>
 #include <fts.h>
+#include <selinux/android.h>
 #include <selinux/selinux.h>
 #include <selinux/label.h>
 
@@ -71,10 +72,14 @@ int main(int argc, char **argv)
 
 	paths[0] = argv[optind];
 
+#ifdef ANDROID
+	hnd = selinux_android_file_context_handle();
+#else
 	selabel_option[0].value = file;
 	selabel_option[1].value = validate;
 
 	hnd = selabel_open(SELABEL_CTX_FILE, selabel_option, 2);
+#endif
 	if (!hnd) {
 		fprintf(stderr, "ERROR: selabel_open - Could not obtain "
 							     "handle:  %s\n",