How to compile .c code from Cython with gcc
Try:
gcc -c -IC:\Python27\include -o ctest.o ctest.c
gcc -shared -LC:\Python27\libs -o ctest.pyd ctest.o -lpython27
-shared creates a shared library. -lpython27 links with the import library C:\Python27\libs\libpython27.a.
That is a linker (ld) error and not a compiler error. You should provide the path to the library (-l and -L) and not only to the headers (-I).