Add C23's memset_explicit().

https://open-std.org/jtc1/sc22/wg14/www/docs/n2897.htm

Test: treehugger
Change-Id: Ia0cfc72bdf3c22eda6a4fc9adaa4c0ca0ff9a7c8
diff --git a/libc/Android.bp b/libc/Android.bp
index b7cb59d..aef6090 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1110,6 +1110,7 @@
         "bionic/mbrtoc16.cpp",
         "bionic/mbrtoc32.cpp",
         "bionic/mempcpy.cpp",
+        "bionic/memset_explicit.cpp",
         "bionic/mkdir.cpp",
         "bionic/mkfifo.cpp",
         "bionic/mknod.cpp",