libstdc++ headers in the header search path, otherwise libstdc++'s
use of #include_next to include Glibc headers breaks.
svn path=/nixpkgs/trunk/; revision=12195
to the gcc invocation.
If we pass a flag like -Wl, then gcc will call the linker unless it
can figure out that it has to do something else (e.g., because of a
"-c" flag). So if no non-flag arguments are given, don't pass any
linker flags. This catches cases like "gcc" (should just print
"gcc: no input files") and "gcc -v" (should print the version).
svn path=/nixpkgs/trunk/; revision=8644
