Minor linux fixes for Cython example

Author: dabeaz

src/15/Makefile

@@ -1,2 +1,5 @@
 osx::
 	gcc -shared -undefined dynamic_lookup sample.c -o libsample.so
+
+linux::
+	gcc -shared -fPIC sample.c -o libsample.so

src/15/wrapping_existing_c_code_with_cython/setup.py

@@ -7,7 +7,8 @@
               ["sample.pyx"],
               include_dirs=['..'],
               libraries=['sample'],
-              library_dirs=['..'])]
+              library_dirs=['..'],
+              runtime_library_dirs=['..'])]
 setup(
   name = 'Sample extension module',
   cmdclass = {'build_ext': build_ext},

src/15/wrapping_existing_c_code_with_cython/setup_alt.py

@@ -7,6 +7,7 @@
               ["sample_alt.pyx"],
               include_dirs=['..'],
               libraries=['sample'],
+              runtime_library_dirs=['..'],
               library_dirs=['..'])]
 setup(
   name = 'Sample extension module',