self-hosting build problem with a build from yesterday's CO and todays revision 101919

Trying to rebuild clang (revision 101919) with a clang from a CO on 20100419, I get:

    ... === configuring in projects/sample (/home/herrold/rpmbuild/BUILD/clang-20100420/projects/sample)
configure: running /bin/sh ./configure --prefix=/usr '--libexecdir=/usr/bin' '--libdir=/usr/lib64' '--enable-targets=host,x86,x86_64,cpp' '--without-ocaml' '--enable-optimized' '--enable-debug-runtime' '--enable-doxygen' '--disable-static' '--with-gnu-ld' '--enable-bindings=none' 'CC=/usr/bin/clang' 'CFLAGS=-g0 -O2 -pipe ' 'CPPFLAGS=-I/usr/include/c++/4.1.1/x86_64-redhat-linux/ ' 'CXX=/usr/bin/clang++' --cache-file=/dev/null --srcdir=.
configure: creating ./config.status
config.status: creating Makefile.common
config.status: executing setup commands
config.status: executing Makefile commands
config.status: executing lib/Makefile commands
config.status: executing lib/sample/Makefile commands
config.status: executing tools/Makefile commands
config.status: executing tools/sample/Makefile commands
+ make DESTDIR=/var/tmp/clang-0.0.20100420.cvs.root
   prefix=/usr libdir=/usr/lib64
make[1]: Entering directory `/home/herrold/rpmbuild/BUILD/clang-20100420/lib/System'
llvm[1]: Compiling Alarm.cpp for Release build
llvm[1]: Compiling Atomic.cpp for Release build
In file included from Atomic.cpp:14:
In file included from /home/herrold/rpmbuild/BUILD/clang-20100420/include/llvm/System/Atomic.h:17:
In file included from /home/herrold/rpmbuild/BUILD/clang-20100420/include/llvm/System/DataTypes.h:35:
/usr/include/c++/4.1.2/cmath:49:10: fatal error: 'bits/c++config.h' file not found
#include <bits/c++config.h>
          ^
1 error generated.
make[1]: *** [/home/herrold/rpmbuild/BUILD/clang-20100420/lib/System/Release/Atomic.o] Error 1
make[1]: Leaving directory `/home/herrold/rpmbuild/BUILD/clang-20100420/lib/System'
make: *** [all] Error 1
error: Bad exit status from /var/tmp/rpm-tmp.88449 (%build)

RPM build errors:
     Bad exit status from /var/tmp/rpm-tmp.88449 (%build)

real 3m9.395s
user 0m4.940s
sys 0m6.476s