use builtin instead of inline memcpy

Author: michaelrj-google

libc/src/string/stpcpy.cpp

@@ -8,7 +8,6 @@
 
 #include "src/string/stpcpy.h"
 #include "src/__support/macros/config.h"
-#include "src/string/memory_utils/inline_memcpy.h"
 #include "src/string/string_utils.h"
 
 #include "src/__support/common.h"
@@ -18,7 +17,7 @@ namespace LIBC_NAMESPACE_DECL {
 LLVM_LIBC_FUNCTION(char *, stpcpy,
                    (char *__restrict dest, const char *__restrict src)) {
   size_t size = internal::string_length(src) + 1;
-  inline_memcpy(dest, src, size);
+  __builtin_memcpy(dest, src, size);
   char *result = dest + size;
 
   if (result != nullptr)