do not bother running ldconfig on DESTDIR.  it wants to write the temp cache
file outside of the chroot.  doesnt matter anyways as we wont use the cache
results (portage will rebuild cache), so running ldconfig is simply a waste
of time.

diff -durN glibc-2.10.1.orig/Makefile glibc-2.10.1/Makefile
--- glibc-2.10.1.orig/Makefile	2009-04-23 20:23:03.000000000 +0200
+++ glibc-2.10.1/Makefile	2009-11-13 00:49:49.000000000 +0100
@@ -116,6 +116,7 @@
 	rm -f $(symbolic-link-list)
 
 install:
+dont-bother-with-destdir:
 	-test ! -x $(common-objpfx)elf/ldconfig || LC_ALL=C LANGUAGE=C \
 	  $(common-objpfx)elf/ldconfig $(addprefix -r ,$(install_root)) \
 				       $(slibdir) $(libdir)