fix ninja version inconsistent

README.md

@@ -16,7 +16,7 @@ build system.
 #### Dependencies
 
  - [Python](https://python.org) (version 3.5 or newer)
- - [Ninja](https://ninja-build.org) (version 1.5 or newer)
+ - [Ninja](https://ninja-build.org) (version 1.7 or newer)
 
 #### Installing from source
 

mesonbuild/backend/ninjabackend.py

@@ -294,7 +294,7 @@ int dummy;
     def generate(self):
         ninja = environment.detect_ninja_command_and_version(log=True)
         if ninja is None:
-            raise MesonException('Could not detect Ninja v1.5 or newer')
+            raise MesonException('Could not detect Ninja v1.7 or newer')
         (self.ninja_command, self.ninja_version) = ninja
         outfilename = os.path.join(self.environment.get_build_dir(), self.ninja_filename)
         tempfilename = outfilename + '~'
@@ -303,7 +303,7 @@ int dummy;
                           self.build.get_project())
             outfile.write('# It is autogenerated by the Meson build system.\n')
             outfile.write('# Do not edit by hand.\n\n')
-            outfile.write('ninja_required_version = 1.5.1\n\n')
+            outfile.write('ninja_required_version = 1.7.1\n\n')
 
             num_pools = self.environment.coredata.backend_options['backend_max_links'].value
             if num_pools > 0: