Fix wheel building

builder/build-wheels.sh

@@ -1,6 +1,11 @@
 #!/bin/bash
 set -e -x
 
+CC=cc
+CXX=c++
+
+export CC CXX
+
 # Install a system package required by our library
 #yum install -y atlas-devel
 yum install -y cmake3 gsl-devel zlib-devel

setup.py

@@ -157,7 +157,7 @@ class BuildCMakeExt(build_ext):
         cython_code = os.path.join(str(build_dir.absolute()),'mycython')
         with open(cython_code, mode="wt") as ff:
           ff.write("#!/bin/sh\n"
-                   "${PYTHON} -c 'from Cython.Compiler.Main import setuptools_main; setuptools_main()' $@")
+                   f"{sys.executable} -c 'from Cython.Compiler.Main import setuptools_main; setuptools_main()' $@")
         os.chmod(cython_code, stat.S_IXUSR|stat.S_IWUSR|stat.S_IRUSR|stat.S_IRGRP)
 
         # Now that the necessary directories are created, build