Original patch from gentoo: gentoo/src/patchsets/gcc/4.3.1/gentoo/08_all_gcc-4.1-cross-compile.patch
Some notes on the 'bootstrap with or without libc headers' debate:
http://linuxfromscratch.org/pipermail/lfs-dev/2005-July/052409.html
http://gcc.gnu.org/ml/gcc/2005-07/msg01195.html

diff -durN gcc-4.3.1.orig/gcc/configure gcc-4.3.1/gcc/configure
--- gcc-4.3.1.orig/gcc/configure	2008-05-21 10:54:15.000000000 +0200
+++ gcc-4.3.1/gcc/configure	2008-06-10 14:57:42.000000000 +0200
@@ -13283,7 +13283,7 @@
 	    | powerpc*-*-*,powerpc64*-*-*)
 		CROSS="$CROSS -DNATIVE_CROSS" ;;
 	esac
-elif test "x$TARGET_SYSTEM_ROOT" != x; then
+elif test "x$TARGET_SYSTEM_ROOT" != x -o $build != $host; then
         SYSTEM_HEADER_DIR=$build_system_header_dir
 fi
 
diff -durN gcc-4.3.1.orig/gcc/configure.ac gcc-4.3.1/gcc/configure.ac
--- gcc-4.3.1.orig/gcc/configure.ac	2008-05-21 10:54:15.000000000 +0200
+++ gcc-4.3.1/gcc/configure.ac	2008-06-10 14:57:42.000000000 +0200
@@ -1749,7 +1749,7 @@
 	    | powerpc*-*-*,powerpc64*-*-*)
 		CROSS="$CROSS -DNATIVE_CROSS" ;;
 	esac
-elif test "x$TARGET_SYSTEM_ROOT" != x; then
+elif test "x$TARGET_SYSTEM_ROOT" != x -o $build != $host; then
         SYSTEM_HEADER_DIR=$build_system_header_dir 
 fi
 
diff -durN gcc-4.3.1.orig/gcc/unwind-dw2.c gcc-4.3.1/gcc/unwind-dw2.c
--- gcc-4.3.1.orig/gcc/unwind-dw2.c	2007-07-25 20:14:57.000000000 +0200
+++ gcc-4.3.1/gcc/unwind-dw2.c	2008-06-10 14:57:42.000000000 +0200
@@ -334,9 +334,11 @@
 }
 #endif
 
+#ifndef inhibit_libc
 #ifdef MD_UNWIND_SUPPORT
 #include MD_UNWIND_SUPPORT
 #endif
+#endif
 
 /* Extract any interesting information from the CIE for the translation
    unit F belongs to.  Return a pointer to the byte after the augmentation,