[cxx-interop][SwiftCompilerSources] Remove redundant SWIFT_IMPORT_UNSAFE

`OptionalInt` is not an unsafe type in Swift, so the attribute has no effect.

Author: egorzhdan

include/swift/SIL/SILBridging.h

@@ -940,7 +940,7 @@ struct BridgedInstruction {
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedGlobalVar GlobalAccessInst_getGlobal() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedGlobalVar AllocGlobalInst_getGlobal() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedFunction FunctionRefBaseInst_getReferencedFunction() const;
-  SWIFT_IMPORT_UNSAFE BRIDGED_INLINE OptionalInt IntegerLiteralInst_getValue() const;
+  BRIDGED_INLINE OptionalInt IntegerLiteralInst_getValue() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedStringRef StringLiteralInst_getValue() const;
   BRIDGED_INLINE int StringLiteralInst_getEncoding() const;
   BRIDGED_INLINE SwiftInt TupleExtractInst_fieldIndex() const;