CLI: remove obsolete -Xbuiltins-from-sources

Looks like it has no effect anymore after 3f2e996803.

compiler/cli/cli-common/gen/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArgumentsCopyGenerated.kt

@@ -15,7 +15,6 @@ fun copyCommonCompilerArguments(from: CommonCompilerArguments, to: CommonCompile
     to.apiVersion = from.apiVersion
     to.autoAdvanceApiVersion = from.autoAdvanceApiVersion
     to.autoAdvanceLanguageVersion = from.autoAdvanceLanguageVersion
-    to.builtInsFromSources = from.builtInsFromSources
     to.checkPhaseConditions = from.checkPhaseConditions
     to.checkStickyPhaseConditions = from.checkStickyPhaseConditions
     to.commonSources = from.commonSources?.copyOf()

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt

@@ -573,16 +573,6 @@ Warning: This mode is not backward compatible and might cause compilation errors
             field = value
         }
 
-    @Argument(
-        value = "-Xbuiltins-from-sources",
-        description = "Compile built-ins from sources."
-    )
-    var builtInsFromSources = false
-        set(value) {
-            checkFrozen()
-            field = value
-        }
-
     @Argument(
         value = "-Xexpect-actual-classes",
         description = """'expect'/'actual' classes (including interfaces, objects, annotations, enums, and 'actual' typealiases) are in Beta.
@@ -756,7 +746,6 @@ The corresponding calls' declarations may not be marked with @BuilderInference."
             )
             put(AnalysisFlags.extendedCompilerChecks, extendedCompilerChecks)
             put(AnalysisFlags.allowKotlinPackage, allowKotlinPackage)
-            put(AnalysisFlags.builtInsFromSources, builtInsFromSources)
             put(AnalysisFlags.muteExpectActualClassesWarning, expectActualClasses)
             put(AnalysisFlags.allowFullyQualifiedNameInKClass, true)
             put(AnalysisFlags.dontWarnOnErrorSuppression, dontWarnOnErrorSuppression)