Propagate LANG environment variable to lint in RBE

Without LANG, lint's text output is ASCII instead of UTF-8, causing
differences between local and remote execution.

Bug: 181681346
Bug: 182415460
Test: m USE_RBE=true RBE_LINT=true
Change-Id: I0ad54aa731582c9b54abb80f50ba508c75992b91
diff --git a/java/lint.go b/java/lint.go
index f8a5180..9f677db 100644
--- a/java/lint.go
+++ b/java/lint.go
@@ -422,6 +422,7 @@
 				"ANDROID_SDK_HOME",
 				"SDK_ANNOTATIONS",
 				"LINT_OPTS",
+				"LANG",
 			},
 			Platform: map[string]string{remoteexec.PoolKey: pool},
 		}).NoVarTemplate(ctx.Config()))