build: pass -fno-ident in Windows gitian descriptor

This prevents compilers from emitting compiler name and
version number info that can needlessly bloat binaries.

Accepted by Clang and GCC. See:

https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-qn

https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#index-fno-ident

Author: fanquake

contrib/gitian-descriptors/gitian-win.yml

@@ -34,8 +34,8 @@ script: |
   CONFIGFLAGS="--enable-reduce-exports --disable-bench --disable-gui-tests"
   FAKETIME_HOST_PROGS="ar ranlib nm windres strip objcopy"
   FAKETIME_PROGS="date makensis zip"
-  HOST_CFLAGS="-O2 -g"
-  HOST_CXXFLAGS="-O2 -g"
+  HOST_CFLAGS="-O2 -g -fno-ident"
+  HOST_CXXFLAGS="-O2 -g -fno-ident"
 
   export QT_RCC_TEST=1
   export QT_RCC_SOURCE_DATE_OVERRIDE=1