Add stpcpy/stpncpy.

Add tests for the above.

Add the fortify implementations of __stpcpy_chk and __stpncpy_chk.

Modify the strncpy test to cover more cases and use this template for
stpncpy.

Add all of the fortify test cases.

Bug: 13746695
Change-Id: I8c0f0d4991a878b8e8734fff12c8b73b07fdd344

libc/bionic/__strcpy_chk.cpp

@@ -26,6 +26,8 @@
  * SUCH DAMAGE.
  */
 
+#undef _FORTIFY_SOURCE
+
 #include <string.h>
 #include <stdlib.h>
 #include "private/libc_logging.h"
@@ -41,7 +43,7 @@
  * This strcpy check is called if _FORTIFY_SOURCE is defined and
  * greater than 0.
  */
-extern "C" char* __strcpy_chk (char* dest, const char* src, size_t dest_len) {
+extern "C" char* __strcpy_chk(char* dest, const char* src, size_t dest_len) {
   // TODO: optimize so we don't scan src twice.
   size_t src_len = strlen(src) + 1;
   if (__predict_false(src_len > dest_len)) {