Checking -fPIC Failed when building the gcc 4.5.1 with --enable-plugin on cygwin

[Lucky Lu <Lucky.Lu@xxxxxxxxxxxxxxxxxx>]

I am having trouble with building the gcc 4.5.1 with --enable-plugin on Cygwin.
The configure string is "--enable-plugin --enable-languages=c,c++ --disable-bootstrap".
The error is ,
  checking for -rdynamic... objdump: conftest: not a dynamic object no
  checking for library containing dlopen... none required
  checking for -fPIC -shared... no
  configure: error:
  Building GCC with plugin support requires a host that supports
  -fPIC, -shared, -ldl and -rdynamic.
  make[1]: *** [configure-gcc] Error 1

When I jump the -fPIC checking, it's success. And then failed when building a gcc plugin, print following,

  plugin.c:1:0: warning: -fPIC ignored for target (all code is position independent)
  /tmp/ccU93aXF.o:plugin.c:(.text+0xd1): undefined reference to `_build3_stat'
  /tmp/ccU93aXF.o:plugin.c:(.text+0xff): undefined reference to `_gimple_assign_single_p'
  .....

Thanks.