Mark x86_64-w64-mingw32,x86_64-pc-linux-gnu broken.

I couldn't get this sample to build. I tried rolling ct-ng back to 1.22
and back to the commit that introduced it, to no avail. Not sure if it
ever built on my machine.

The first problem is the failure to build binutils/gold because of the
missing <pthread.h> in mingw. However, even if CT_BINUTILS_GOLD_THREADS
option is unset, the build dies in configure of the pass-1 of the core CC.
The config.log states that it failed to link with libmpfr.a, which has
a lot of undefined references to symbols like '__imp___iob_func'.
Googling shows that these symbols are some dark Cygwin/MinGW magic and I
do not have the knowledge of these arcana. Let some other MinGWizard fix
it another day.

Signed-off-by: Alexey Neyman <stilor@att.net>

samples/x86_64-w64-mingw32,x86_64-pc-linux-gnu/crosstool.config

@@ -1,6 +1,4 @@
 CT_EXPERIMENTAL=y
-CT_DEBUG_CT=y
-CT_DEBUG_CT_SAVE_STEPS=y
 CT_LOCAL_TARBALLS_DIR="${HOME}/src"
 CT_SAVE_TARBALLS=y
 # CT_STRIP_HOST_TOOLCHAIN_EXECUTABLES is not set