Port Android port to older Android systems

* exec/config.h.in: Autoheader.
* exec/configure.ac: Check for declarations of stpcpy and
stpncpy.
* exec/exec.c (stpcpy, stpncpy): Use replacements if
declarations are not present; this happens when a new Android
NDK is building for an old version of Android.

exec/config.h.in

@@ -38,6 +38,14 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. */
 /* Define to number of the `exec' system call. */
 #undef EXEC_SYSCALL
 
+/* Define to 1 if you have the declaration of `stpcpy', and to 0 if you don't.
+   */
+#undef HAVE_DECL_STPCPY
+
+/* Define to 1 if you have the declaration of `stpncpy', and to 0 if you
+   don't. */
+#undef HAVE_DECL_STPNCPY
+
 /* Define to 1 if you have the `getpagesize' function. */
 #undef HAVE_GETPAGESIZE
 

exec/configure.ac

@@ -55,6 +55,7 @@ AC_TYPE_PID_T
 
 AC_HEADER_STDBOOL
 AC_CHECK_FUNCS([getpagesize stpcpy stpncpy])
+AC_CHECK_DECLS([stpcpy, stpncpy])
 
 AH_BOTTOM([
 #ifdef HAVE_STDBOOL_H

exec/exec.c

@@ -50,7 +50,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 /* Define replacements for required string functions.  */
 
-#ifndef HAVE_STPCPY
+#if !defined HAVE_STPCPY || !defined HAVE_DECL_STPCPY
 
 /* Copy SRC to DEST, returning the address of the terminating '\0' in
    DEST.  */
@@ -72,14 +72,14 @@ rpl_stpcpy (char *dest, const char *src)
 }
 
 #define stpcpy rpl_stpcpy
-#endif /* !HAVE_STPCPY */
+#endif /* !defined HAVE_STPCPY || !defined HAVE_DECL_STPCPY */
 
-#ifndef HAVE_STPNCPY
+#if !defined HAVE_STPNCPY || !defined HAVE_DECL_STPNCPY
 
 /* Copy no more than N bytes of SRC to DST, returning a pointer past
    the last non-NUL byte written into DST.  */
 
-char *
+static char *
 rpl_stpncpy (char *dest, const char *src, size_t n)
 {
   char c, *s;
@@ -140,7 +140,7 @@ rpl_stpncpy (char *dest, const char *src, size_t n)
 }
 
 #define stpncpy rpl_stpncpy
-#endif /* !HAVE_STPNCPY */
+#endif /* !defined HAVE_STPNCPY || !defined HAVE_DECL_STPNCPY */