(jm_FUNC_UNLINK_BUSY_TEXT): New file/macro.

From J. David Anglin.

m4/unlink-busy.m4

@@ -0,0 +1,32 @@
+#serial 4
+
+dnl From J. David Anglin.
+
+dnl HPUX and other systems can't unlink shared text that is being executed.
+
+AC_DEFUN(jm_FUNC_UNLINK_BUSY_TEXT,
+[dnl
+  AC_CACHE_CHECK([whether a program can unlink itself],
+    jm_cv_func_unlink_busy_text,
+    [
+      AC_TRY_RUN([
+        main (argc, argv)
+          int argc;
+          char **argv;
+        {
+          if (!argc)
+            exit (-1);
+          exit (unlink (argv[0]));
+        }
+	],
+      jm_cv_func_unlink_busy_text=yes,
+      jm_cv_func_unlink_busy_text=no,
+      jm_cv_func_unlink_busy_text=no
+      )
+    ]
+  )
+
+  if test $jm_cv_func_unlink_busy_text = no; then
+    INSTALL=$ac_install_sh
+  fi
+])