compile fails on hypot

[Benjamin Kosnik]

I just checked in a fix for this. After that checking, I was able to 
build both with and without shadow headers.

-benjamin

> /local/larsbj/gcc/build/gcc/g++ -B/local/larsbj/gcc/build/gcc/ -nostdinc++ -L/lo
> cal/larsbj/gcc/build/i586-pc-linux-gnu/libstd++-v3/src -L/local/larsbj/gcc/build
> D_GNU_SOURCE -D_ISOC99_SOURCE -nostdinc++ -I../../../../libstdc++-v3/include/std -I../../../../libstdc++-v3/include/c_std -I../../../../libstdc++-v3/libsupc++ -I../../../../libstdc++-v3/include -I../libio -I../../../../libstdc++-v3/libio -I../../../../libstdc++-v3/libmath -I../include -I/usr/local/include -g -O2 -fvtable-thunks -D_GNU_SOURCE -fno-implicit-templates -Wall -Wno-format -W -Wwrite-strings -Winline -fdiagnostics-show-location=once -ffunction-sections -fdata-sections -fno-builtin -g -c ../../../../libstdc++-v3/src/complex.cc  -fPIC -DPIC -o .libs/complex.o
> ../../../../libstdc++-v3/include/bits/std_complex.h:955: redefinition of
>    `template<class _Tp>, std::complex<_Tp> std::conj(const std::complex<_Tp>&)'
> ../../../../libstdc++-v3/include/bits/std_complex.h:55: `template<class _Tp>,
>    std::complex<_Tp> std::conj(const std::complex<_Tp>&)' previously declared
>    here
> make[3]: *** [complex.lo] Error 1