maint: import the xmemdup0 gnulib module.

* bootstrap.conf: Require this module.
* src/parse-gram.y: Include xmemdup0.h.

bootstrap.conf

@@ -26,7 +26,8 @@ gnulib_modules='
   quote quotearg realloc-posix
   spawn-pipe stdbool stpcpy strdup-posix strerror strtoul strverscmp
   unistd unistd-safer unlocked-io update-copyright unsetenv verify
-  warnings xalloc xalloc-die xstrndup
+  warnings
+  xalloc xalloc-die xmemdup0 xstrndup
 
   fprintf-posix printf-posix snprintf-posix sprintf-posix
   vsnprintf-posix vsprintf-posix

lib/.gitignore

@@ -265,3 +265,5 @@
 /xsize.h
 /xstrndup.c
 /xstrndup.h
+/xmemdup0.c
+/xmemdup0.h

src/parse-gram.y

@@ -32,6 +32,7 @@
 #include "symlist.h"
 #include "scan-gram.h"
 #include "scan-code.h"
+#include "xmemdup0.h"
 
 #define YYLLOC_DEFAULT(Current, Rhs, N)  (Current) = lloc_default (Rhs, N)
 static YYLTYPE lloc_default (YYLTYPE const *, int);