Allow running native executable in cross build

Make so both executable() targets that are marked as native and
external programs (which are usually build tools compiled for the
host machine) are not supposed to be run with the exe wrapper.

mesonbuild/backend/backends.py

@@ -200,11 +200,15 @@ class Backend():
         with open(exe_data, 'wb') as f:
             if isinstance(exe, dependencies.ExternalProgram):
                 exe_fullpath = exe.fullpath
+                exe_needs_wrapper = False
             elif isinstance(exe, (build.BuildTarget, build.CustomTarget)):
                 exe_fullpath = [self.get_target_filename_abs(exe)]
+                exe_needs_wrapper = exe.is_cross
             else:
                 exe_fullpath = [exe]
-            is_cross = self.environment.is_cross_build() and \
+                exe_needs_wrapper = False
+            is_cross = exe_needs_wrapper and \
+                self.environment.is_cross_build() and \
                 self.environment.cross_info.need_cross_compiler() and \
                 self.environment.cross_info.need_exe_wrapper()
             if is_cross: