Prevent kotlinc from reading /tmp/build.txt

Pass -Didea.plugins.compatible.build=999.SNAPSHOT to kotlinc and kapt
to prevent it from reading /tmp/build.txt and failing with an obscure
exception:
exception: java.lang.ExceptionInInitializerError
	at com.intellij.openapi.util.BuildNumber.currentVersion(BuildNumber.java:297)
...

Bug: 222162908
Test: m metalava with /tmp/build.txt present
Change-Id: I5faced4a2e94561ce3aa37bfaacf5bd7d988a4f0

java/config/kotlin.go

@@ -47,4 +47,9 @@ func init() {
 	pctx.StaticVariable("KotlincSuppressJDK9Warnings", strings.Join([]string{
 		"-J--add-opens=java.base/java.util=ALL-UNNAMED", // https://youtrack.jetbrains.com/issue/KT-43704
 	}, " "))
+
+	pctx.StaticVariable("KotlincGlobalFlags", strings.Join([]string{
+		// b/222162908: prevent kotlinc from reading /tmp/build.txt
+		"-Didea.plugins.compatible.build=999.SNAPSHOT",
+	}, " "))
 }