should fix previous problems with GCC 4.3 in compiling C++ code
where e.g. <cassert> has to appear before <assert.h> in the search
path due to the former's use of #include_next. The previous "fix"
broke compilation of C code by placing the C++ include directory
before the Glibc include directory (which would barf on
e.g. <complex.h>, which appears in both).
svn path=/nixpkgs/branches/stdenv-updates/; revision=13806
72822ebbc0