RFA: AVR: Support building AVR Linux targets

[Nick Clifton]

Hi Dennis, Hi Anatoly, Hi Eric,

  I have run into a small problem building GCC for an AVR Linux target -
  glibc-c.o is not being built.  It turns out that the section handling
  "avr-*-*" in the config.gcc file is redefining tmake_file without
  allowing for the fact that t-glibc has already been added to it.

  The patch below is the obvious fix for this problem, but I have not
  committed it because it occurred to me that there might be some AVR
  specific reason for not including t-glibc.  So - is the patch OK, or
  is there some other way of fixing the problem ?

Cheers
  Nick

gcc/ChangeLog
2013-08-12  Nick Clifton  <nickc@redhat.com>

	* config.gcc (avr-*-*): Allow for tmake_file not being empty.

Index: gcc/config.gcc
===================================================================
--- gcc/config.gcc	(revision 201658)
+++ gcc/config.gcc	(working copy)
@@ -1001,7 +1001,7 @@
 	    tm_file="${tm_file} ${cpu_type}/avrlibc.h"
 	    tm_defines="${tm_defines} WITH_AVRLIBC"
 	fi
-	tmake_file="avr/t-avr avr/t-multilib"
+	tmake_file="${tmake_file} avr/t-avr avr/t-multilib"
 	use_gcc_stdint=wrap
 	extra_gcc_objs="driver-avr.o avr-devices.o"
 	extra_objs="avr-devices.o avr-log.o"