The commit prior to this one, "gcc: fix c++ headers when same
triplet cross compiling" causes gcc's c++ headers to be in the same
outpath subdirectory regardless of whether the gcc build is a
host==target or host!=target compiler.
As a result of that change, the hack in cc-wrapper which adapted to
the different paths is no longer needed. And, in fact, it must be
removed, since if it is left in place builds such as
pkgsCross.aarch64-multiplatform.firefox will fail as shown below.
```
firefox-unwrapped> 0:02.01(B checking the host C compiler works... yes(B(B
firefox-unwrapped> 0:02.01(B checking for the host C++ compiler... /nix/store/1asqji9djmdlapzs70q7jw2j308ry7cn-clang-wrapper-16.0.6/bin/c++(B(B
firefox-unwrapped> 0:02.14(B checking whether the host C++ compiler can be used... yes(B(B
firefox-unwrapped> 0:02.14(B checking the host C++ compiler version... 16.0.6(B(B
firefox-unwrapped> 0:02.21(B checking the host C++ compiler works... yes(B(B
firefox-unwrapped> 0:02.40(B checking for target linker... lld(B(B
firefox-unwrapped> 0:02.51(B checking for host linker... lld(B(B
firefox-unwrapped> 0:02.60(B checking for 64-bit OS... yes(B(B
firefox-unwrapped> 0:02.67(B checking for new enough STL headers from libstdc++...(B(B
firefox-unwrapped> 0:02.67(B DEBUG: <truncated - see config.log for full output>(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | #if defined(__GLIBCXX__) && !defined(_GLIBCXX_RELEASE)(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | # error libstdc++ not new enough(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | #endif(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | #if defined(_GLIBCXX_RELEASE)(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | # if _GLIBCXX_RELEASE < 8(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | # error libstdc++ not new enough(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | # else(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | (void) 0(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | # endif(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | #endif(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | ;(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | return 0;(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | }(B(B
firefox-unwrapped> 0:02.67(B DEBUG: Executing: `/nix/store/7v4bi4q334yircaznwm353h1l5i7k98f-aarch64-unknown-linux-gnu-clang-wrapper-16.0.6/bin/aarch64-unknown-linux-gnu-clang++ /build/conftest.qvbo58dv.cpp -c`(B(B
firefox-unwrapped> 0:02.67(B DEBUG: The command returned non-zero exit status 1.(B(B
firefox-unwrapped> 0:02.67(B DEBUG: Its error output was:(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | /build/conftest.qvbo58dv.cpp:1:10: fatal error: 'cstddef' file not found(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | #include <cstddef>(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | ^~~~~~~~~(B(B
firefox-unwrapped> 0:02.67(B DEBUG: | 1 error generated.(B(B
firefox-unwrapped> 0:02.67(B ERROR: The libstdc++ in use is not new enough. Please run ./mach bootstrap to update your compiler, or update your system libstdc++ installation.(B(B
firefox-unwrapped> *** Fix above errors and then restart with "./mach build"
error: build of '/nix/store/5in7xkji5hzqkl14ygwq3vxnni54lykk-firefox-unwrapped-aarch64-unknown-linux-gnu-119.0.1.drv' on 'ssh://root@192.168.22.103' failed: builder for '/nix/store/5in7xkji5hzqkl14ygwq3vxnni54lykk-firefox-unwrapped-aarch64-unknown-linux-gnu-119.0.1.drv' failed with exit code 1
error: builder for '/nix/store/5in7xkji5hzqkl14ygwq3vxnni54lykk-firefox-unwrapped-aarch64-unknown-linux-gnu-119.0.1.drv' failed with exit code 1;
```
When build platform and host platform differ, but have the same
triple, the code in nixpkgs will consider it a cross compilation,
but gcc won't. This will lead some derivations to look for c++
headers in the wrong place. To solve this always output the headers
in the non-cross location, like we do for the other gcc headers
already.
