buy back changes from rfe2711212 - recompile bug

ChangeLog

@@ -10,6 +10,7 @@
 	              to man page and vtund.conf sample.
  	             Remove doubled if(send_a_file){...} block in linkfd.c.
 	pat2951972 - reduce connection chatter
+	rfe2711212 - improve linking on rebuilds (hmld)
 	
 3.0.2:
 	rfe1685781 - vtun3 client should parse vtun2 server encr directives (hch)

aclocal.m4

@@ -0,0 +1,72 @@
+dnl Test files
+AC_DEFUN( AC_TEST_FILES,
+[
+    ac_file_found=yes
+    for f in $1; do
+	if test ! -f $2/$f; then
+    	   ac_file_found=no
+	   break;
+	fi
+    done
+
+    if test "$ac_file_found" = "yes" ; then
+	ifelse([$3], , :,[$3])
+    else
+	ifelse([$4], , :,[$4])
+    fi
+])
+
+dnl Search for headers, add path to CPPFLAGS if found 
+AC_DEFUN( AC_SEARCH_HEADERS, 
+[
+    AC_MSG_CHECKING("for $1") 
+    ac_hdr_found=no
+    for p in $2; do
+	if test -n "$p"; then
+	  dir="$p"
+	else
+	  dir="/usr/include"
+	fi
+	AC_TEST_FILES($1, $dir, 
+	    [ 
+     	       ac_hdr_found=yes
+	       break
+	    ]
+	)
+    done 
+    if test "$ac_hdr_found" = "yes" ; then
+	if test -n "$p"; then
+	  CPPFLAGS="$CPPFLAGS -I$p"
+	fi
+        AC_MSG_RESULT( [($dir) yes] ) 
+	ifelse([$3], , :,[$3])
+    else
+        AC_MSG_RESULT("no") 
+	ifelse([$4], , :,[$4])
+    fi
+])
+
+
+dnl Create links to all files($1) in the directory($2)
+AC_DEFUN( AC_LINK_DIR, 
+[
+    for i in $1; do
+      dnl if test -f $2/$i -a ! -f $i; then
+      if test -f $2/$i; then
+         AC_MSG_RESULT(linking $2/$i  to  $i)
+         ln -f -s $2/$i $i
+      fi
+    done 
+])
+
+dnl Create driver and protocol links
+dnl $1 - drivers list, $2 - os dir
+AC_DEFUN( AC_LINK_DRV, 
+[
+    AC_MSG_RESULT( creating driver and protocol links ... )
+
+    AC_LINK_DIR($1, generic)
+    if test "$2" != ""; then
+       AC_LINK_DIR($1, $2)
+    fi
+])