Link failure for tor-print-ed-signing-cert.exe on Windows

Currently Tor fails to build on Windows because of:

  CCLD     src/tools/tor-print-ed-signing-cert.exe
/usr/bin/i686-w64-mingw32-ld: /home/user/src/github.com/ahf/tor-win32/prefix/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0x100d): undefined reference to `_imp__GetDeviceCaps@8'
/usr/bin/i686-w64-mingw32-ld: /home/user/src/github.com/ahf/tor-win32/prefix/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0x103b): undefined reference to `_imp__CreateCompatibleBitmap@12'
/usr/bin/i686-w64-mingw32-ld: /home/user/src/github.com/ahf/tor-win32/prefix/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0x105d): undefined reference to `_imp__GetObjectA@12'
/usr/bin/i686-w64-mingw32-ld: /home/user/src/github.com/ahf/tor-win32/prefix/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0x113d): undefined reference to `_imp__GetDIBits@28'
/usr/bin/i686-w64-mingw32-ld: /home/user/src/github.com/ahf/tor-win32/prefix/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0x11a1): undefined reference to `_imp__DeleteObject@4'

This is because we are missing to include the library from @TOR_LIB_GDI@. Patch coming up.