I had configured and built GCC 3.4.4 with "--with-arch=pentium3" and was happily using it for everything till I decided to compile glibc 2.3.5 with it. The build failed with a weird assembler error message as noted in glibc bug-701. That bug however, had been been closed unceremoniously and marked a duplicate of bug-333, which itself looks unnecessarily obnoxious.
After a bit of poking around, I found out that GCC pre-defines "__i686" if "-march=pentium3" is used (see $GCC_SRC_DIR/gcc/config/i386/i386.h) and this was causing the problem with glibc (see $GLIBC_SRC_DIR/sysdeps/i386/elf/setjmp.S). So I had to explicitly use "-march=i386" with GCC to be able to compile glibc. However, "make check" still fails. I will now build and install a vanilla GCC 3.4.4 and see if that is able to properly build glibc.