Revert "avrlibc: hook up libdir for cc-wrapper"

This reverts commit b2844f89d1.

It broke simavr:

  $ nix-build -A simavr
  [...]
  /nix/store/3k4djrsq23m2yg9ar4h1lkkz1ijv0ghv-avr-binutils-2.41/bin/avr-ld: /nix/store/3rpyzla18mbj690hv7j5dang0kd3c1fq-avr-libc-avr-2.1.0/avr/lib/libc.a(vfprintf_std.o): in function `.L15':
  vfprintf.c:(.text.avr-libc+0xd8): undefined reference to `__mulqi3'
  /nix/store/3k4djrsq23m2yg9ar4h1lkkz1ijv0ghv-avr-binutils-2.41/bin/avr-ld: /nix/store/3rpyzla18mbj690hv7j5dang0kd3c1fq-avr-libc-avr-2.1.0/avr/lib/libc.a(vfprintf_std.o): in function `.L18':
  vfprintf.c:(.text.avr-libc+0xe4): undefined reference to `__mulqi3'
  collect2: error: ld returned 1 exit status
  make[1]: *** [../Makefile.common:161: atmega644_adc_test.axf] Error 1
  make[1]: Leaving directory '/build/source/tests'
  make: *** [Makefile:21: build-tests] Error 2

Fixes #295610.

pkgs/build-support/bintools-wrapper/default.nix

@@ -325,6 +325,12 @@ stdenv.mkDerivation {
       hardening_unsupported_flags+=" relro bindnow"
     ''
 
+    + optionalString (libc != null && targetPlatform.isAvr) ''
+      for isa in avr5 avr3 avr4 avr6 avr25 avr31 avr35 avr51 avrxmega2 avrxmega4 avrxmega5 avrxmega6 avrxmega7 tiny-stack; do
+        echo "-L${getLib libc}/avr/lib/$isa" >> $out/nix-support/libc-cflags
+      done
+    ''
+
     + optionalString stdenv.targetPlatform.isDarwin ''
       echo "-arch ${targetPlatform.darwinArch}" >> $out/nix-support/libc-ldflags
     ''

pkgs/build-support/cc-wrapper/default.nix

@@ -668,6 +668,12 @@ stdenv.mkDerivation {
       hardening_unsupported_flags+=" stackprotector"
     ''
 
+    + optionalString (libc != null && targetPlatform.isAvr) ''
+      for isa in avr5 avr3 avr4 avr6 avr25 avr31 avr35 avr51 avrxmega2 avrxmega4 avrxmega5 avrxmega6 avrxmega7 tiny-stack; do
+        echo "-B${getLib libc}/avr/lib/$isa" >> $out/nix-support/libc-crt1-cflags
+      done
+    ''
+
     + optionalString stdenv.targetPlatform.isDarwin ''
         echo "-arch ${targetPlatform.darwinArch}" >> $out/nix-support/cc-cflags
     ''

pkgs/development/misc/avr/libc/default.nix

@@ -19,7 +19,6 @@ stdenv.mkDerivation rec {
 
   passthru = {
     incdir = "/avr/include";
-    libdir = "/avr/lib";
   };
 
   meta = with lib; {