buildman: add option -E for treating compiler warnings as errors

Add a new option '-E' for treating all compiler warnings as errors.
Eventually this will pass 'KCFLAGS=-Werror' to Kbuild.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

tools/buildman/builderthread.py

@@ -216,6 +216,8 @@ class BuilderThread(threading.Thread):
                     args.append('-s')
                 if self.builder.num_jobs is not None:
                     args.extend(['-j', str(self.builder.num_jobs)])
+                if self.builder.warnings_as_errors:
+                    args.append('KCFLAGS=-Werror')
                 config_args = ['%s_defconfig' % brd.target]
                 config_out = ''
                 args.extend(self.builder.toolchains.GetMakeArguments(brd))