meson: remove autotools checking stuffs

autotools has been removed. so that the autotools checking logic is not needed.
this patch removes them.

Reviewed-by: Marcel Hollerbach <mail@marcel-hollerbach.de>
Differential Revision: https://phab.enlightenment.org/D9198

meson.build

@@ -8,11 +8,6 @@ if host_machine.system() == 'darwin'
   add_languages('objc')
 endif
 
-clean_check = run_command('meson/clean_check.sh')
-if clean_check.returncode() == 0
-  error('Meson build requires a clean source tree')
-endif
-
 pkgconfig = import('pkgconfig')
 
 test_env = environment()

meson/clean_check.sh

@@ -1,3 +0,0 @@
-#!/bin/sh
-
-test -f ${MESON_SOURCE_ROOT}/configure