re PR plugins/53126 (gcc-4.7.0 error "gcc-ar: Cannot find plugin")

	PR plugins/53126
	* gcc-ar.c (main): If GCC_EXEC_PREFIX is set in env,
	append program name to it and pass that as first argument
	to make_relative_prefix.  Always pass standard_libexec_prefix
	as last argument to make_relative_prefix.  If
	make_relative_prefix returns NULL, fall back to
	standard_libexec_prefix.

From-SVN: r187090

gcc/ChangeLog

 2012-05-03  Jakub Jelinek  <jakub@redhat.com>
 
+	PR plugins/53126
+	* gcc-ar.c (main): If GCC_EXEC_PREFIX is set in env,
+	append program name to it and pass that as first argument
+	to make_relative_prefix.  Always pass standard_libexec_prefix
+	as last argument to make_relative_prefix.  If
+	make_relative_prefix returns NULL, fall back to
+	standard_libexec_prefix.
+
 	PR debug/53174
 	* tree-predcom.c (remove_stmt): Call reset_debug_uses on stmts being
 	removed.

gcc/gcc-ar.c

 /* Wrapper for ar/ranlib/nm to pass the LTO plugin.
-   Copyright (C) 2011 Free Software Foundation, Inc.
+   Copyright (C) 2011, 2012 Free Software Foundation, Inc.
    Contributed by Andi Kleen.
 
 This file is part of GCC.
@@ -52,11 +52,16 @@ main(int ac, char **av)
   /* XXX implement more magic from gcc.c? */
   nprefix = getenv ("GCC_EXEC_PREFIX");
   if (!nprefix)
+    nprefix = av[0];
+  else
+    nprefix = concat (nprefix, "gcc-" PERSONALITY, NULL);
+
+  nprefix = make_relative_prefix (nprefix,
+				  standard_bin_prefix,
+				  standard_libexec_prefix);
+  if (nprefix == NULL)
     nprefix = standard_libexec_prefix;
 
-  nprefix = make_relative_prefix (av[0], 
-				  standard_bin_prefix, 
-				  nprefix);
   plugin = concat (nprefix,
 		   dir_separator,
                    DEFAULT_TARGET_MACHINE,