build: make --dry-run work again on all

build-doc

@@ -27,11 +27,12 @@ https://github.com/cirosantilli/linux-kernel-module-cheat#build-the-documentatio
         )
         error_re = re.compile('^asciidoctor: WARNING: ')
         exit_status = 0
-        with open(self.env['build_doc_log']) as f:
-            for line in f:
-                if error_re.search(line):
-                    exit_status = 1
-                    break
+        if not self.env['dry_run']:
+            with open(self.env['build_doc_log']) as f:
+                for line in f:
+                    if error_re.search(line):
+                        exit_status = 1
+                        break
         return exit_status
 
 if __name__ == '__main__':

build-gem5

@@ -64,7 +64,8 @@ https://github.com/cirosantilli/linux-kernel-module-cheat-regression#gem5-unit-t
                     self.env['gem5_source_dir'], LF,
                 ])
             else:
-                raise Exception('gem5 submodule not checked out')
+                if not self.env['dry_run']:
+                    raise Exception('gem5 submodule not checked out')
         if self.env['verbose']:
             verbose = ['--verbose', LF]
         else: