trouble building: missing libc.map

[Steve Summit]

I'm trying to build glibc, and it's failing because the file
libc.map is missing.  (Exact error message below.)

There are a bunch of built map files (libm.map, librt.map, etc.)
in the build directory, but not for libc itself.  I might have
deleted libc.map at one point, thinking it might help to correct
a different build problem I was having, and imagining it would be
rebuilt automatically.  But somehow I seem to have confused the
make system into not rebuilding it at all.

Anybody know which step constructs libc.map, or how to force that
step?  I could start over with `make clean`, I know, but I've got
an astonishingly slow build environment, so I'd rather not.

Here's the error message itself:

gcc   -shared -static-libgcc -Wl,-O1  -Wl,-z,defs -Wl,-dynamic-linker=/lib64/ld-linux-x86-64.so.2   -B/home/scs/glibc/build/csu/  -Wl,--version-script=/home/scs/glibc/build/libc.map -Wl,-soname=libc.so.6 -Wl,-z,relro  -nostdlib -nostartfiles -e __libc_main -L/home/scs/glibc/build -L/home/scs/glibc/build/math -L/home/scs/glibc/build/elf -L/home/scs/glibc/build/dlfcn -L/home/scs/glibc/build/nss -L/home/scs/glibc/build/nis -L/home/scs/glibc/build/rt -L/home/scs/glibc/build/resolv -L/home/scs/glibc/build/mathvec -L/home/scs/glibc/build/support -L/home/scs/glibc/build/misc -L/home/scs/glibc/build/debug -L/home/scs/glibc/build/nptl -Wl,-rpath-link=/home/scs/glibc/build:/home/scs/glibc/build/math:/home/scs/glibc/build/elf:/home/scs/glibc/build/dlfcn:/home/scs/glibc/build/nss:/home/scs/glibc/build/nis:/home/scs/glibc/build/rt:/home/scs/glibc/build/resolv:/home/scs/glibc/build/mathvec:/home/scs/glibc/build/support:/home/scs/glibc/build/misc:/home/scs/glibc/build/debug:/home/scs/glibc/build/np
 tl -o /home/scs/glibc/build/libc.so /home/scs/glibc/build/csu/abi-note.o /home/scs/glibc/build/libc_pic.os.clean /home/scs/glibc/build/elf/interp.os /home/scs/glibc/build/elf/ld.so -lgcc /home/scs/glibc/build/elf/sofini.os
/usr/bin/ld: cannot open linker script file /home/scs/glibc/build/libc.map: No such file or directory
collect2: error: ld returned 1 exit status
make[2]: *** [../Makerules:654: /home/scs/glibc/build/libc.so] Error 1