AppImage: Patch Python sysconfigdata

When building in docker on macOS, python builds with .exe extension
because the case insensitive file system of macOS leaks into docker.
This causes the build to result in a different output on macOS compared
to Linux. We simply patch sysconfigdata to remove the extension.

Some more info: https://bugs.python.org/issue27631

contrib/build-linux/appimage/build.sh

@@ -57,6 +57,12 @@ tar xf "$CACHEDIR/Python-$PYTHON_VERSION.tar.xz" -C "$BUILDDIR"
       -q
     make -j4 -s
     make -s install > /dev/null
+    # When building in docker on macOS, python builds with .exe extension because the
+    # case insensitive file system of macOS leaks into docker. This causes the build
+    # to result in a different output on macOS compared to Linux. We simply patch
+    # sysconfigdata to remove the extension.
+    # Some more info: https://bugs.python.org/issue27631
+    sed -i -e 's/\.exe//g' "$APPDIR"/usr/lib/python3.6/_sysconfigdata*
 )