complibs: fixup the host complibs install dir

It's easier to have as much as possible stuff in the same place to
ease backup/restore, and make things easier to follow.

Move the host companion libraries install dir as a sub-dir of the
build-tools install dir (but not directly in it, it would break
for canadian or cross-native).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 --- gcc-4.1.2.orig/libstdc++-v3/include/c_std/std_cstdio.h	2005-10-30 23:21:50.000000000 +0100

 +++ gcc-4.1.2/libstdc++-v3/include/c_std/std_cstdio.h	2007-03-04 23:33:27.000000000 +0100

 @@ -143,7 +143,7 @@

    using ::vsprintf;

  }

 -#if _GLIBCXX_USE_C99

 +#if _GLIBCXX_USE_C99 || defined(__UCLIBC__)

  #undef snprintf

  #undef vfscanf