[RootFS] New PlatformSupport artifacts without old MinGW headers

[giordano]

Companion PR to JuliaPackaging/Yggdrasil#11828. Fix JuliaPackaging/Yggdrasil#4067.

[giordano]

sandbox:${WORKSPACE} # make -C /usr/share/testsuite install
make: Entering directory '/usr/share/testsuite'
make[1]: Entering directory '/usr/share/testsuite/c/dyn_link'
cc -shared -o /tmp/testsuite/x86_64-w64-mingw32/c/dyn_link/libfoo/libfoo.dll -fPIC -g -O2 -lm libfoo/libfoo.c
libfoo/libfoo.c:1:0: warning: -fPIC ignored for target (all code is position independent) [enabled by default]
 #include <stdio.h>
 ^
cc -o /tmp/testsuite/x86_64-w64-mingw32/c/dyn_link/dyn_link.exe -I/usr/share/testsuite/c/dyn_link/libfoo -fPIC -g -O2 -L/tmp/testsuite/x86_64-w64-mingw32/c/dyn_link/libfoo -lfoo dyn_link.c
dyn_link.c:1:0: warning: -fPIC ignored for target (all code is position independent) [enabled by default]
 #include <stdio.h>
 ^
make[1]: Leaving directory '/usr/share/testsuite/c/dyn_link'
make[1]: Entering directory '/usr/share/testsuite/c/hello_world'
cc -o /tmp/testsuite/x86_64-w64-mingw32/c/hello_world/hello_world.exe -g -O2 hello_world.c
make[1]: Leaving directory '/usr/share/testsuite/c/hello_world'
make[1]: Entering directory '/usr/share/testsuite/c/openmp'
gcc -o /tmp/testsuite/x86_64-w64-mingw32/c/openmp/openmp.exe -g -O2 -fopenmp openmp.c
make[1]: Leaving directory '/usr/share/testsuite/c/openmp'
make[1]: Entering directory '/usr/share/testsuite/cxx/dyn_link'
c++ -shared -o /tmp/testsuite/x86_64-w64-mingw32/cxx/dyn_link/librepeater/librepeater.dll -fPIC -g -O2 -lm librepeater/librepeater.cc
librepeater/librepeater.cc:1:0: warning: -fPIC ignored for target (all code is position independent) [enabled by default]
 #include <string>
 ^
c++ -o /tmp/testsuite/x86_64-w64-mingw32/cxx/dyn_link/dyn_link.exe -I/usr/share/testsuite/cxx/dyn_link/librepeater -fPIC -g -O2 -L/tmp/testsuite/x86_64-w64-mingw32/cxx/dyn_link/librepeater -lrepeater dyn_link.cc
dyn_link.cc:1:0: warning: -fPIC ignored for target (all code is position independent) [enabled by default]
 #include <iostream>
 ^
make[1]: Leaving directory '/usr/share/testsuite/cxx/dyn_link'
make[1]: Entering directory '/usr/share/testsuite/cxx/hello_world'
c++ -o /tmp/testsuite/x86_64-w64-mingw32/cxx/hello_world/hello_world.exe -g -O2 hello_world.cc
make[1]: Leaving directory '/usr/share/testsuite/cxx/hello_world'
make[1]: Entering directory '/usr/share/testsuite/fortran/hello_world'
gfortran -o /tmp/testsuite/x86_64-w64-mingw32/fortran/hello_world/hello_world.o -c hello_world.f
cc -o /tmp/testsuite/x86_64-w64-mingw32/fortran/hello_world/hello_world.exe -g -O2 /tmp/testsuite/x86_64-w64-mingw32/fortran/hello_world/hello_world.o -lgfortran -lm -lquadmath
gfortran -o /tmp/testsuite/x86_64-w64-mingw32/fortran/hello_world/hello_world.exe hello_world.f
make[1]: Leaving directory '/usr/share/testsuite/fortran/hello_world'
make: Leaving directory '/usr/share/testsuite'

Looks good, as far as this can test.