meson: Remove the python option

We can instead rely solely on Meson's Python module, as Meson supports
specifying the `python` binary to use.

meson.build

@@ -43,10 +43,7 @@ if cc.has_header('android/api-level.h')
   host_os = 'android'
 endif
 
-python = get_option('python')
-if python == ''
-  python = import('python').find_installation()
-endif
+python = import('python').find_installation()
 
 python_incdir = get_option('python_incdir')
 if python_incdir == ''

meson.options

@@ -1,9 +1,3 @@
-option('python',
-  type: 'string',
-  value: '',
-  description: 'Python interpreter to build for'
-)
-
 option('python_incdir',
   type: 'string',
   value: '',