SecureAI.app on old macOS versions

[mrjbq7]

When building the binary with clang, it uses current version:

Before:

$ otool -l SecureAI.app/Contents/MacOS/SecureAI
…
      cmd LC_BUILD_VERSION
  cmdsize 32
 platform 1
    minos 14.0
      sdk 14.0
   ntools 1
     tool 3
  version 1022.1

After 7bc36f0:

$ otool -l SecureAI.app/Contents/MacOS/SecureAI
…
      cmd LC_BUILD_VERSION
  cmdsize 32
 platform 1
    minos 11.0
      sdk 11.0
   ntools 1
     tool 3
  version 1022.1

We also need to make sure python is built for earlier macOS, which it appears (on my machine) to be:

$ otool -l SecureAI.app/Contents/Resources/python/bin/* | grep minos
    minos 11.0
    minos 11.0