:bug: Add `-fPIC` to  `CFLAGS` for Arch `x86_64` (#2085)
:bug: Add `-fPIC` to  `CFLAGS` for Arch `x86_64` (#2085)

Since, at this point, we know that we need to add the mentioned flags at
some point, let's be brave and try to add it at Arch level (since we
need `-fPIC` for `ArchARMv7_a` it may be also the case for `Archx86_64`)

**See also:**
  - https://github.com/kivy/python-for-android/pull/2073#issuecomment-592998163
PKRoma/python-for-android,rnixx/python-for-android,germn/python-for-android,germn/python-for-android,germn/python-for-android,germn/python-for-android,kronenpj/python-for-android,kronenpj/python-for-android,rnixx/python-for-android,kivy/python-for-android,kivy/python-for-android,rnixx/python-for-android,kronenpj/python-for-android,kronenpj/python-for-android,rnixx/python-for-android,kivy/python-for-android,kivy/python-for-android,PKRoma/python-for-android,rnixx/python-for-android,kronenpj/python-for-android,germn/python-for-android,PKRoma/python-for-android,kivy/python-for-android,germn/python-for-android,PKRoma/python-for-android,rnixx/python-for-android,PKRoma/python-for-android