closes bpo-37965: Fix compiler warning of distutils CCompiler.test_function. (GH-15560)

https://bugs.python.org/issue37965

https://bugs.python.org/issue37965

Automerge-Triggered-By: @benjaminp
(cherry picked from commit 55aabee0)
Co-authored-by: Anonymous Maarten <madebr@users.noreply.github.com>

Lib/distutils/ccompiler.py

@@ -748,8 +748,9 @@ class CCompiler:
             for incl in includes:
                 f.write("""#include "%s"\n""" % incl)
             f.write("""\
-main (int argc, char **argv) {
+int main (int argc, char **argv) {
     %s();
+    return 0;
 }
 """ % funcname)
         finally:

Misc/NEWS.d/next/Library/2019-08-28-14-04-18.bpo-37965.7xGE-C.rst

+Fix C compiler warning caused by distutils.ccompiler.CCompiler.has_function.